Daily Archives: October 11, 2018

DisruptOps: What Security Managers Need to Know About Amazon S3 Exposures (1/2)

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As we spin up Disrupt:OPS we are beginning to post cloud-specific content over there, mixing theory with practical how-to guidance. Not to worry! We have plenty of content still planned for Securosis. But we haven’t added any staff at Securosis so there is only so much we can write. In the meantime, linking to non-product posts from Securosis should help ensure you don’t lose sleep over missing even a single cloud-related blog entry.

So here’s #1 from the Disrupt:Ops hit parade!

What Security Managers Need to Know About Amazon S3 Exposures (1/2)

The accidental (or deliberate) exposure of sensitive data on Amazon S3 is one of those deceptively complex issues. On the surface it seems entirely simple to avoid, yet despite wide awareness we see a constant stream of public exposures and embarrassments, combined with a healthy dollop of misunderstanding and victim blaming.

Read the full post at DisruptOps

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New documents reveal details of the FBI’s dangerous practice of impersonating journalists

RCFP

FBI policy governing journalist impersonation, released by Reporters Committee for Freedom of the Press

Trust between journalists and their sources is paramount. When first approached by journalists, sources or subjects of stories can often be skeptical of a journalist’s motives—or even question whether they are really a journalist at all. Reporters often find themselves in life or death situations when when speaking with members of armed militias, accused terrorists, government rebels, or in myriad other cases.  

So every time a government agent impersonates a journalist to conduct its own investigation, they are putting countless other real journalists at physical risk.

Yet for years, the FBI has engaged in the impersonation of journalists and has defended its practice at the highest level—while keeping its exact policies that govern the tactic. Thanks to documents released as part of a Freedom of Information Act lawsuit by Reporters Committee for Freedom of the Press, we now know a little more.

Back in 2007, a man identifying himself as a reporter with the Associated Press approached a 15 year old high school student online and asked him to review an article about threats to his school for accuracy. But he wasn’t a real reporter, and it wasn’t real article.

Instead, the man was a FBI agent impersonating a journalist in an attempt to catch a suspect accused of making bomb threats. The faked article sent to the student included malware that revealed his computer’s location and IP address, allowing the FBI to confirm details about the suspect’s identity.

When this became public in 2015, backlash from the press and public was swift and intense. Press freedom advocates and the Associated Press itself raised serious concerns that this tactic could endanger journalists and undermine public trust in news gathering.

"This latest revelation of how the FBI misappropriated the trusted name of The Associated Press doubles our concern and outrage...about how the agency's unacceptable tactics undermine AP and the vital distinction between the government and the press," Kathleen Carroll, then-execute editor of the AP, said in a statement.

Despite the criticism, then-FBI director James Comey defended the agency impersonating journalists in the New York Times, and the FBI’s inspector general also signed off on the controversial practice.

In an even more disturbing incident in 2015, FBI posed as a documentary filmmaker crew in order to gain the trust of a group of ranchers engaged in an armed standoff with the government. The fake crew recorded hundreds of hours of video and audio and spent months with the ranchers pretending to make a documentary.

In response to these harrowing incidents, Reporters Committee for Freedom of the Press (RCFP) has been working to uncover the details of FBI’s tactic of impersonating journalists. It is engaged in multiple FOIA lawsuits about the practice—one that relates to the AP case from 2007, and one about impersonation of filmmakers, which led to this most recent disclosure.

This week, after fighting the government for years in court, they finally obtained the FBI’s internal policies for impersonating journalists.

The records show that in order to impersonate a journalist, a FBI field office is supposed to submit an application to do so with the Undercover Review Committee at FBI headquarters and it must be approved by the FBI Deputy Director after consultation with the Deputy Attorney General.

“We’ve understood for a long time that the FBI engages in this practice, so I think it’s helpful for the public to understand the internal rules it utilizes when engaging in it,” said Jen Nelson, a staff attorney at RCFP.

While we know the FBI has impersonated members of the press on multiple occasions, it’s possible that other agencies have also done so as part of their operations. Freedom of the Press Foundation has filed FOIA requests with over a dozen other federal agencies seeking more information.

RCFP continues to work to uncover the details and frequency of the FBI’s use of the tactic, which poses huge chilling effects for journalism.

The FBI’s own arguments in the case acknowledge the chilling effect on journalism presented by this tactic. In a motion of summary judgment obtained by Freedom of the Press Foundation, the agency argued that it should not be required to disclose details about other instances of media impersonation, on the grounds that “it would allow criminals to judge whether they should completely avoid any contacts with documentary film crews, rendering the investigative technique ineffective.”

“That’s our entire point,” said Nelson. “By impersonating members of the media, the FBI causes significant harm to the institution of journalism and undermines the practice.”

The FBI should immediately halt its use of the tactic, which poses real and significant dangers to journalists, who may have to deal with suspicion of being federal agents while going about their work. And the public also suffers when sources may be more reluctant to bring critical information to the press because they may not know who is a real journalist and who is fake.

If the agency refuses to do so, Congress has the ability to step in and ban the practice by law. Many lawmakers have defended press freedom in the fact of attacks on it by the president, and this would be a powerful way to protect countless journalists nationwide.

High Performance Web Brute-Forcing 🕸🐏

Finding and exploiting bespoke attacks on web applications is, of-course, exciting… but I find that performing the most simple of attacks, but as efficiently and effectively as possible, can also feel pretty damn rewarding.

In this short post i’ll show you how writing just a few lines of code can have immense gains on web request brute-force attacks, versus using the tools you would probably reach for right now (let’s be honest, it’s Burp).

The task shares huge commonality with offline password cracking; where performance and strategy are everything. Much like a lot of my colleagues who are totally hooked on password cracking, i find the problem of effective web brute-forcing a seriously  under-appreciated art.

As a rather contrived example, let’s say we wanted to brute-force Wikipedia pages looking for the word ‘Luftballons’.

We’ll start with our base URL of https://en.wikipedia.org/wiki/(that’s a zero), and increment 0 until we find ‘Luftballons’, on page 99.

Lets see that attack in python using the Requests module:

import httplib,time, requests
 
from timeit import default_timer as timer
 
start = timer()
 
for x in range(0,100):
 
	r = requests.get('https://en.wikipedia.org/wiki/' + str(x))
 
	if 'Luftballons' in r.text:
 
		print (timer() - start)

Execution time: 13.9255948067 seconds. Horrendously slow.

Now, I know what you might be thinking… is Requests too high an API to work at speed? Is it bloated and slow compared to say, using raw sockets or something from the standard libary? Well, absolutely not. For a starter, Request is built on the speedy urllib3, but comes with a bunch of smart benefits we’re already taking advantage of without realising:

  • The gzip and deflate transfer-encodings are supported, so we can receive compressed server responses. This means there is less data on the wire, and we can move more of it in the same amount of time. The benefit is far superior to the processing time required to pack and unpack the server responses.
  • Persistent DNS. Contrary to what I have read on StackOverflow, using Requests with a single TCP connection does not appear to trigger DNS resolution on each request, it seems to do it once. If you can imaging having to do a full DNS resolve for each request, as some libraries might, the performance hit would be significant.

The problem then, is we are just using Requests really inefficiently.

It doesn’t seem to be common knowledge, but Burp opens up a new TCP connection for every single Intruder request, which has a huge overhead on long brute-force attacks. This is what our script was doing too. Lets see what happens if we modify it to reuse the same connection:

print 'Trying with requests single connection'
 
start2 = timer()
 
s = requests.Session()
 
for x in range(0,100):
 
	r = s.get('https://en.wikipedia.org/wiki/' + str(x))
 
	if 'Luftballons' in r.text:
 
		print (timer() - start2)

Execution time: 3.16235017776. Much, much faster.

Now if we repeat this attack in Burp, it’ll still have a considerable edge… why? because of threads.

For a short attack like this, Burp’s default of 5 threads keeps it in line with even highly efficient code. But the longer the attack runs, the greater the time wasted to creating new TCP connections. A few hours into an attack and you’ve wasted lots of time.

When Burp says it has 5 thread, what it means is that it can make 5 simultaneous requests via their own connections. But we only have one connection, so lets implement 5 threads that reuse that one connection in our example:

import time, requests
 
from timeit import default_timer as timer
 
from multiprocessing.dummy import Pool as ThreadPool
 

 
start3 = timer()
 
s = requests.Session()
 
payloads = []
 
for x in range(0,100):
 
	payloads.append('https://en.wikipedia.org/wiki/' + str(x))
 

 
def worker6(payload): 
 
	r = s.get(payload)
 
	if 'Luftballons' in r.text:
 
		print (timer() - start3)
 

 
pool = ThreadPool(5) 
 
results = pool.map(worker6, payloads)
 
pool.close() 
 
pool.join()

Execution time: 0.93794298172. Very fast. Under the same conditions, this will stomp all over Burp; and pretty much anything else you can expect to make without considerable effort.

Room for improvement? sure!:

So the main problem with Request, and almost all http libraries, is that they don’t support HTTP Pipelining. HTTP Pipelining is the idea of firing multiple requests through a single TCP connection, without having to wait for each response synchronously. If you look at our last code snippet, it looks like thats exactly what we are doing, but unfortunately we’re not. The Requests library actually locks a TCP connection until it has fully read the response content from the last request. The main reason we are able to get such a big perfomance boost from threads, is that we already have our next requests queued up on the connection and ready to fire the moment it’s available to use by the next worker thread. We’ve effectively just minimised the delay this connection sharing was causing us. Pipelining has its own issues, for example its not supported on all webserver, and connection issues are much harder to deal with if you have bits of multiple requests already in transit.

To get around these limitations but still reap the performance of asynchronous requests, we can do one obvious thing: increase the amount of connections.

We can wrap our last code snippet into 5 threads of its own. This gives us 5 TCP connections, each working as fast as possible to synchronously fire out requests. This is as close we can easily get to HTTP pipelining, but is arguably a far more stable attack.

If you really want to play with true pipelining, take a look at Ruby’s em-http-request.

Hopefully this gives you some ideas of how to script basic, yet efficient, brute-force attacks. Don’t assume that because a tool already exists for a job that it means it does it best. As a pen-tester, time is precious and we need to spend it wisely.

-Hiburn8

Note: So burp has no time measurement feature in Intruder, so I created a hack to figure out roughly how fast burp is at making requests. Essentially, I created a jython plugin which registers an extension-generated payload for use in Intruder. When this plugin is called upon to create a payload, it returns an empty string payload, but logs the current time in microseconds to the plugin console. This doesn’t give us the exact that time requests were issued or completed… but does help us figure out how fast burp is generating requests to send, which, alone, is twice as slow as the last example here in all of my test cases.

National Cyber Security Awareness Month

October is National Cyber Security Awareness Month (NCSAM), but why restrict it to a month, when we need it all year round. So, I created a few very short videos on a few security awareness topics. The idea was to keep them short enough so people would watch them to the end, have a bit […]

AA18-284A: Publicly Available Tools Seen in Cyber Incidents Worldwide

Original release date: October 11, 2018

Summary

This report is a collaborative research effort by the cyber security authorities of five nations: Australia, Canada, New Zealand, the United Kingdom, and the United States.[1][2][3][4][5]

In it we highlight the use of five publicly available tools, which have been used for malicious purposes in recent cyber incidents around the world. The five tools are:

  1. Remote Access Trojan: JBiFrost
  2. Webshell: China Chopper
  3. Credential Stealer: Mimikatz
  4. Lateral Movement Framework: PowerShell Empire
  5. C2 Obfuscation and Exfiltration: HUC Packet Transmitter

To aid the work of network defenders and systems administrators, we also provide advice on limiting the effectiveness of these tools and detecting their use on a network.

The individual tools we cover in this report are limited examples of the types of tools used by threat actors. You should not consider this an exhaustive list when planning your network defense.

Tools and techniques for exploiting networks and the data they hold are by no means the preserve of nation states or criminals on the dark web. Today, malicious tools with a variety of functions are widely and freely available for use by everyone from skilled penetration testers, hostile state actors and organized criminals, to amateur cyber criminals.

The tools in this Activity Alert have been used to compromise information across a wide range of critical sectors, including health, finance, government, and defense. Their widespread availability presents a challenge for network defense and threat-actor attribution.

Experience from all our countries makes it clear that, while cyber threat actors continue to develop their capabilities, they still make use of established tools and techniques. Even the most sophisticated threat actor groups use common, publicly available tools to achieve their objectives.

Whatever these objectives may be, initial compromises of victim systems are often established through exploitation of common security weaknesses. Abuse of unpatched software vulnerabilities or poorly configured systems are common ways for a threat actor to gain access. The tools detailed in this Activity Alert come into play once a compromise has been achieved, enabling attackers to further their objectives within the victim’s systems.

How to Use This Report

The tools detailed in this Activity Alert fall into five categories: Remote Access Trojans (RATs), webshells, credential stealers, lateral movement frameworks, and command and control (C2) obfuscators.

This Activity Alert provides an overview of the threat posed by each tool, along with insight into where and when it has been deployed by threat actors. Measures to aid detection and limit the effectiveness of each tool are also described.

The Activity Alert concludes with general advice for improving network defense practices.

Technical Details

Remote Access Trojan: JBiFrost 

First observed in May 2015, the JBiFrost RAT is a variant of the Adwind RAT, with roots stretching back to the Frutas RAT from 2012.

A RAT is a program that, once installed on a victim’s machine, allows remote administrative control. In a malicious context, it can—among many other functions—be used to install backdoors and key loggers, take screen shots, and exfiltrate data.

Malicious RATs can be difficult to detect because they are normally designed not to appear in lists of running programs and can mimic the behavior of legitimate applications.

To prevent forensic analysis, RATs have been known to disable security measures (e.g., Task Manager) and network analysis tools (e.g., Wireshark) on the victim’s system.

In Use

JBiFrost RAT is typically employed by cyber criminals and low-skilled threat actors, but its capabilities could easily be adapted for use by state-sponsored threat actors.

Other RATs are widely used by Advanced Persistent Threat (APT) actor groups, such as Adwind RAT, against the aerospace and defense sector; or Quasar RAT, by APT10, against a broad range of sectors.

Threat actors have repeatedly compromised servers in our countries with the purpose of delivering malicious RATs to victims, either to gain remote access for further exploitation, or to steal valuable information such as banking credentials, intellectual property, or PII.

Capabilities

JBiFrost RAT is Java-based, cross-platform, and multifunctional. It poses a threat to several different operating systems, including Windows, Linux, MAC OS X, and Android.

JBiFrost RAT allows threat actors to pivot and move laterally across a network or install additional malicious software. It is primarily delivered through emails as an attachment, usually an invoice notice, request for quotation, remittance notice, shipment notification, payment notice, or with a link to a file hosting service.

Past infections have exfiltrated intellectual property, banking credentials, and personally identifiable information (PII). Machines infected with JBiFrost RAT can also be used in botnets to carry out distributed denial-of-service attacks.

Examples

Since early 2018, we have observed an increase in JBiFrost RAT being used in targeted attacks against critical national infrastructure owners and their supply chain operators. There has also been an increase in the RAT’s hosting on infrastructure located in our countries.

In early 2017, Adwind RAT was deployed via spoofed emails designed to look as if they originated from Society for Worldwide Interbank Financial Telecommunication, or SWIFT, network services.

Many other publicly available RATs, including variations of Gh0st RAT, have also been observed in use against a range of victims worldwide.

Detection and Protection

Some possible indications of a JBiFrost RAT infection can include, but are not limited to:

  • Inability to restart the computer in safe mode,
  • Inability to open the Windows Registry Editor or Task Manager,
  • Significant increase in disk activity and/or network traffic,
  • Connection attempts to known malicious Internet Protocol (IP) addresses, and
  • Creation of new files and directories with obfuscated or random names.

Protection is best afforded by ensuring systems and installed applications are all fully patched and updated. The use of a modern antivirus program with automatic definition updates and regular system scans will also help ensure that most of the latest variants are stopped in their tracks. You should ensure that your organization is able to collect antivirus detections centrally across its estate and investigate RAT detections efficiently.

Strict application whitelisting is recommended to prevent infections from occurring.

The initial infection mechanism for RATs, including JBiFrost RAT, can be via phishing emails. You can help prevent JBiFrost RAT infections by stopping these phishing emails from reaching your users, helping users to identify and report phishing emails, and implementing security controls so that the malicious email does not compromise your device. The United Kingdom National Cyber Security Centre (UK NCSC) has published phishing guidance.

Webshell: China Chopper 

China Chopper is a publicly available, well-documented webshell that has been in widespread use since 2012.

Webshells are malicious scripts that are uploaded to a target host after an initial compromise and grant a threat actor remote administrative capability.

Once this access is established, webshells can also be used to pivot to additional hosts within a network.

In Use

China Chopper is extensively used by threat actors to remotely access compromised web servers, where it provides file and directory management, along with access to a virtual terminal on the compromised device.

As China Chopper is just 4 KB in size and has an easily modifiable payload, detection and mitigation are difficult for network defenders.

Capabilities

China Chopper has two main components: the China Chopper client-side, which is run by the attacker, and the China Chopper server, which is installed on the victim web server but is also attacker-controlled.

The webshell client can issue terminal commands and manage files on the victim server. Its MD5 hash is publicly available (originally posted on hxxp://www.maicaidao.com).

The MD5 hash of the web client is shown in table 1 below.

Table 1: China Chopper webshell client MD5 hash

Webshell ClientMD5 Hash
caidao.exe5001ef50c7e869253a7c152a638eab8a

The webshell server is uploaded in plain text and can easily be changed by the attacker. This makes it harder to define a specific hash that can identify adversary activity. In summer 2018, threat actors were observed targeting public-facing web servers that were vulnerable to CVE-2017-3066. The activity was related to a vulnerability in the web application development platform Adobe ColdFusion, which enabled remote code execution.

China Chopper was intended as the second-stage payload, delivered once servers had been compromised, allowing the threat actor remote access to the victim host. After successful exploitation of a vulnerability on the victim machine, the text-based China Chopper is placed on the victim web server. Once uploaded, the webshell server can be accessed by the threat actor at any time using the client application. Once successfully connected, the threat actor proceeds to manipulate files and data on the web server.

China Chopper’s capabilities include uploading and downloading files to and from the victim using the file-retrieval tool wget to download files from the internet to the target; and editing, deleting, copying, renaming, and even changing the timestamp, of existing files.

Detection and protection

The most powerful defense against a webshell is to avoid the web server being compromised in the first place. Ensure that all the software running on public-facing web servers is up-to-date with security patches applied. Audit custom applications for common web vulnerabilities.[6]

One attribute of China Chopper is that every action generates a hypertext transfer protocol (HTTP) POST. This can be noisy and is easily spotted if investigated by a network defender.

While the China Chopper webshell server upload is plain text, commands issued by the client are Base64 encoded, although this is easily decodable.

The adoption of Transport Layer Security (TLS) by web servers has resulted in web server traffic becoming encrypted, making detection of China Chopper activity using network-based tools more challenging.

The most effective way to detect and mitigate China Chopper is on the host itself—specifically on public-facing web servers. There are simple ways to search for the presence of the web-shell using the command line on both Linux and Windows based operating systems.[7]

To detect webshells more broadly, network defenders should focus on spotting either suspicious process execution on web servers (e.g., Hypertext Preprocessor [PHP] binaries spawning processes) and out-of-pattern outbound network connections from web servers. Typically, web servers make predictable connections to an internal network. Changes in those patterns may indicate the presence of a web shell. You can manage network permissions to prevent web-server processes from writing to directories where PHP can be executed, or from modifying existing files.

We also recommend that you use web access logs as a source of monitoring, such as through traffic analytics. Unexpected pages or changes in traffic patterns can be early indicators.

Credential Stealer: Mimikatz 

Developed in 2007, Mimikatz is mainly used by attackers to collect the credentials of other users, who are logged into a targeted Windows machine. It does this by accessing the credentials in memory within a Windows process called Local Security Authority Subsystem Service (LSASS).

These credentials, either in plain text, or in hashed form, can be reused to give access to other machines on a network.

Although it was not originally intended as a hacking tool, in recent years Mimikatz has been used by multiple actors for malicious purposes. Its use in compromises around the world has prompted organizations globally to re-evaluate their network defenses.

Mimikatz is typically used by threat actors once access has been gained to a host and the threat actor wishes to move throughout the internal network. Its use can significantly undermine poorly configured network security.

In Use

Mimikatz source code is publicly available, which means anyone can compile their own versions of the new tool and potentially develop new Mimikatz custom plug-ins and additional functionality.

Our cyber authorities have observed widespread use of Mimikatz among threat actors, including organized crime and state-sponsored groups.

Once a threat actor has gained local administrator privileges on a host, Mimikatz provides the ability to obtain the hashes and clear-text credentials of other users, enabling the threat actor to escalate privileges within a domain and perform many other post-exploitation and lateral movement tasks.

For this reason, Mimikatz has been bundled into other penetration testing and exploitation suites, such as PowerShell Empire and Metasploit.

Capabilities

Mimikatz is best known for its ability to retrieve clear text credentials and hashes from memory, but its full suite of capabilities is extensive.

The tool can obtain Local Area Network Manager and NT LAN Manager hashes, certificates, and long-term keys on Windows XP (2003) through Windows 8.1 (2012r2). In addition, it can perform pass-the-hash or pass-the-ticket tasks and build Kerberos “golden tickets.”

Many features of Mimikatz can be automated with scripts, such as PowerShell, allowing a threat actor to rapidly exploit and traverse a compromised network. Furthermore, when operating in memory through the freely available “Invoke-Mimikatz” PowerShell script, Mimikatz activity is very difficult to isolate and identify.

Examples

Mimikatz has been used across multiple incidents by a broad range of threat actors for several years. In 2011, it was used by unknown threat actors to obtain administrator credentials from the Dutch certificate authority, DigiNotar. The rapid loss of trust in DigiNotar led to the company filing for bankruptcy within a month of this compromise.

More recently, Mimikatz was used in conjunction with other malicious tools—in the NotPetya and BadRabbit ransomware attacks in 2017 to extract administrator credentials held on thousands of computers. These credentials were used to facilitate lateral movement and enabled the ransomware to propagate throughout networks, encrypting the hard drives of numerous systems where these credentials were valid.

In addition, a Microsoft research team identified use of Mimikatz during a sophisticated cyberattack targeting several high-profile technology and financial organizations. In combination with several other tools and exploited vulnerabilities, Mimikatz was used to dump and likely reuse system hashes.

Detection and Protection

Updating Windows will help reduce the information available to a threat actor from the Mimikatz tool, as Microsoft seeks to improve the protection offered in each new Windows version.

To prevent Mimikatz credential retrieval, network defenders should disable the storage of clear text passwords in LSASS memory. This is default behavior for Windows 8.1/Server 2012 R2 and later, but can be specified on older systems which have the relevant security patches installed.[8] Windows 10 and Windows Server 2016 systems can be protected by using newer security features, such as Credential Guard.

Credential Guard will be enabled by default if:

  • The hardware meets Microsoft’s Windows Hardware Compatibility Program Specifications and Policies for Windows Server 2016 and Windows Server Semi-Annual Branch; and
  • The server is not acting as a Domain Controller.

You should verify that your physical and virtualized servers meet Microsoft’s minimum requirements for each release of Windows 10 and Windows Server.

Password reuse across accounts, particularly administrator accounts, makes pass-the-hash attacks far simpler. You should set user policies within your organization that discourage password reuse, even across common level accounts on a network. The freely available Local Administrator Password Solution from Microsoft can allow easy management of local administrator passwords, preventing the need to set and store passwords manually.

Network administrators should monitor and respond to unusual or unauthorized account creation or authentication to prevent Kerberos ticket exploitation, or network persistence and lateral movement. For Windows, tools such as Microsoft Advanced Threat Analytics and Azure Advanced Threat Protection can help with this.

Network administrators should ensure that systems are patched and up-to-date. Numerous Mimikatz features are mitigated or significantly restricted by the latest system versions and updates. But no update is a perfect fix, as Mimikatz is continually evolving and new third-party modules are often developed.

Most up-to-date antivirus tools will detect and isolate non-customized Mimikatz use and should therefore be used to detect these instances. But threat actors can sometimes circumvent antivirus systems by running Mimikatz in memory, or by slightly modifying the original code of the tool. Wherever Mimikatz is detected, you should perform a rigorous investigation, as it almost certainly indicates a threat actor is actively present in the network, rather than an automated process at work.

Several of Mimikatz’s features rely on exploitation of administrator accounts. Therefore, you should ensure that administrator accounts are issued on an as-required basis only. Where administrative access is required, you should apply privileged access management principles.

Since Mimikatz can only capture the accounts of those users logged into a compromised machine, privileged users (e.g., domain administrators) should avoid logging into machines with their privileged credentials. Detailed information on securing Active Directory is available from Microsoft.[9]

Network defenders should audit the use of scripts, particularly PowerShell, and inspect logs to identify anomalies. This will aid in identifying Mimikatz or pass-the-hash abuse, as well as in providing some mitigation against attempts to bypass detection software.

Lateral Movement Framework: PowerShell Empire 

PowerShell Empire is an example of a post-exploitation or lateral movement tool. It is designed to allow an attacker (or penetration tester) to move around a network after gaining initial access. Other examples of these tools include Cobalt Strike and Metasploit. PowerShell Empire can also be used to generate malicious documents and executables for social engineering access to networks.

The PowerShell Empire framework was designed as a legitimate penetration testing tool in 2015. PowerShell Empire acts as a framework for continued exploitation once a threat actor has gained access to a system.

The tool provides a threat actor with the ability to escalate privileges, harvest credentials, exfiltrate information, and move laterally across a network. These capabilities make it a powerful exploitation tool. Because it is built on a common legitimate application (PowerShell) and can operate almost entirely in memory, PowerShell Empire can be difficult to detect on a network using traditional antivirus tools.

In Use

PowerShell Empire has become increasingly popular among hostile state actors and organized criminals. In recent years we have seen it used in cyber incidents globally across a wide range of sectors.

Initial exploitation methods vary between compromises, and threat actors can configure the PowerShell Empire uniquely for each scenario and target. This, in combination with the wide range of skill and intent within the PowerShell Empire user community, means that the ease of detection will vary. Nonetheless, having a greater understanding and awareness of this tool is a step forward in defending against its use by threat actors.

Capabilities

PowerShell Empire enables a threat actor to carry out a range of actions on a victim’s machine and implements the ability to run PowerShell scripts without needing powershell.exe to be present on the system Its communications are encrypted and its architecture is flexible.

PowerShell Empire uses "modules" to perform more specific malicious actions. These modules provide the threat actor with a customizable range of options to pursue their goals on the victim’s systems. These goals include escalation of privileges, credential harvesting, host enumeration, keylogging, and the ability to move laterally across a network.

PowerShell Empire’s ease of use, flexible configuration, and ability to evade detection make it a popular choice for threat actors of varying abilities.

Examples

During an incident in February 2018, a UK energy sector company was compromised by an unknown threat actor. This compromise was detected through PowerShell Empire beaconing activity using the tool’s default profile settings. Weak credentials on one of the victim’s administrator accounts are believed to have provided the threat actor with initial access to the network.

In early 2018, an unknown threat actor used Winter Olympics-themed socially engineered emails and malicious attachments in a spear-phishing campaign targeting several South Korean organizations. This attack had an additional layer of sophistication, making use of Invoke-PSImage, a stenographic tool that will encode any PowerShell script into an image.

In December 2017, APT19 targeted a multinational law firm with a phishing campaign. APT19 used obfuscated PowerShell macros embedded within Microsoft Word documents generated by PowerShell Empire.

Our cybersecurity authorities are also aware of PowerShell Empire being used to target academia. In one reported instance, a threat actor attempted to use PowerShell Empire to gain persistence using a Windows Management Instrumentation event consumer. However, in this instance, the PowerShell Empire agent was unsuccessful in establishing network connections due to the HTTP connections being blocked by a local security appliance.

Detection and Protection

Identifying malicious PowerShell activity can be difficult due to the prevalence of legitimate PowerShell activity on hosts and the increased use of PowerShell in maintaining a corporate environment.

To identify potentially malicious scripts, PowerShell activity should be comprehensively logged. This should include script block logging and PowerShell transcripts.

Older versions of PowerShell should be removed from environments to ensure that they cannot be used to circumvent additional logging and controls added in more recent versions of PowerShell. This page provides a good summary of PowerShell security practices.[10]

The code integrity features in recent versions of Windows can be used to limit the functionality of PowerShell, preventing or hampering malicious PowerShell in the event of a successful intrusion.

A combination of script code signing, application whitelisting, and constrained language mode will prevent or limit the effect of malicious PowerShell in the event of a successful intrusion. These controls will also impact legitimate PowerShell scripts and it is strongly advised that they be thoroughly tested before deployment.

When organizations profile their PowerShell usage, they often find it is only used legitimately by a small number of technical staff. Establishing the extent of this legitimate activity will make it easier to monitor and investigate suspicious or unexpected PowerShell usage elsewhere on the network.

C2 Obfuscation and Exfiltration: HUC Packet Transmitter 

Attackers will often want to disguise their location when compromising a target. To do this, they may use generic privacy tools (e.g., Tor) or more specific tools to obfuscate their location.

HUC Packet Transmitter (HTran) is a proxy tool used to intercept and redirect Transmission Control Protocol (TCP) connections from the local host to a remote host. This makes it possible to obfuscate an attacker’s communications with victim networks. The tool has been freely available on the internet since at least 2009.

HTran facilitates TCP connections between the victim and a hop point controlled by a threat actor. Malicious threat actors can use this technique to redirect their packets through multiple compromised hosts running HTran to gain greater access to hosts in a network.

In Use

The use of HTran has been regularly observed in compromises of both government and industry targets.

A broad range of threat actors have been observed using HTran and other connection proxy tools to

  • Evade intrusion and detection systems on a network,
  • Blend in with common traffic or leverage domain trust relationships to bypass security controls,
  • Obfuscate or hide C2 infrastructure or communications, and
  • Create peer-to-peer or meshed C2 infrastructure to evade detection and provide resilient connections to infrastructure.
Capabilities

HTran can run in several modes, each of which forwards traffic across a network by bridging two TCP sockets. They differ in terms of where the TCP sockets are initiated from, either locally or remotely. The three modes are

  • Server (listen) – Both TCP sockets initiated remotely;
  • Client (slave) – Both TCP sockets initiated locally; and
  • Proxy (tran) – One TCP socket initiated remotely, the other initiated locally, upon receipt of traffic from the first connection.

HTran can inject itself into running processes and install a rootkit to hide network connections from the host operating system. Using these features also creates Windows registry entries to ensure that HTran maintains persistent access to the victim network.

Examples

Recent investigations by our cybersecurity authorities have identified the use of HTran to maintain and obfuscate remote access to targeted environments.

In one incident, the threat actor compromised externally-facing web servers running outdated and vulnerable web applications. This access enabled the upload of webshells, which were then used to deploy other tools, including HTran.

HTran was installed into the ProgramData directory and other deployed tools were used to reconfigure the server to accept Remote Desktop Protocol (RDP) communications.

The threat actor issued a command to start HTran as a client, initiating a connection to a server located on the internet over port 80, which forwards RDP traffic from the local interface.

In this case, HTTP was chosen to blend in with other traffic that was expected to be seen originating from a web server to the internet. Other well-known ports used included:

  • Port 53 – Domain Name System
  • Port 443 - HTTP over TLS/Secure Sockets Layer
  • Port 3306 - MySQL
  • By using HTran in this way, the threat actor was able to use RDP for several months without being detected.
Detection and Protection

Attackers need access to a machine to install and run HTran, so network defenders should apply security patches and use good access control to prevent attackers from installing malicious applications.

Network monitoring and firewalls can help prevent and detect unauthorized connections from tools such as HTran.

In some of the samples analyzed, the rootkit component of HTran only hides connection details when the proxy mode is used. When client mode is used, defenders can view details about the TCP connections being made.

HTran also includes a debugging condition that is useful for network defenders. In the event that a destination becomes unavailable, HTran generates an error message using the following format:

sprint(buffer, “[SERVER]connection to %s:%d error\r\n”, host, port2);

This error message is relayed to the connecting client in the clear. Network defenders can monitor for this error message to potentially detect HTran instances active in their environments.

 

Mitigations

There are several measures that will improve the overall cybersecurity of your organization and help protect it against the types of tools highlighted in this report. Network defenders are advised to seek further information using the links below.

Further information: invest in preventing malware-based attacks across various scenarios. See UK NCSC Guidance: https://www.ncsc.gov.uk/guidance/mitigating-malware.

Additional Resources from International Partners

Contact Information

NCCIC encourages recipients of this report to contribute any additional information that they may have related to this threat. For any questions related to this report, please contact NCCIC at

NCCIC encourages you to report any suspicious activity, including cybersecurity incidents, possible malicious code, software vulnerabilities, and phishing-related scams. Reporting forms can be found on the NCCIC/US-CERT homepage at http://www.us-cert.gov/.

Feedback

NCCIC strives to make this report a valuable tool for our partners and welcomes feedback on how this publication could be improved. You can help by answering a few short questions about this report at the following URL: https://www.us-cert.gov/forms/feedback.

References

Revisions

  • October, 11 2018: Initial version

This product is provided subject to this Notification and this Privacy & Use policy.


ICS Tactical Security Trends: Analysis of the Most Frequent Security Risks Observed in the Field

Introduction

FireEye iSIGHT Intelligence compiled extensive data from dozens of ICS security health assessment engagements (ICS Healthcheck) performed by Mandiant, FireEye's consulting team, to identify the most pervasive and highest priority security risks in industrial facilities. The information was acquired from hands-on assessments carried out over the last few years across a broad range of industries, including manufacturing, mining, automotive, energy, chemical, natural gas, and utilities. In this post, we provide details of these risks, and indicate best practices and recommendations to mitigate the identified risks.

Mandiant ICS Healthchecks

Mandiant ICS Healthchecks and penetration testing engagements include on-site assessments of customers' IT and ICS systems. The ICS Healthcheck consists of workshops and technical reviews. It captures the results in a final report that ranks discovered findings and vulnerabilities by risk using Mandiant’s Risk Rating method. During an onsite workshop with site technical experts, Mandiant develops a technical understanding of the subject control system(s), builds a network diagram of the control system, analyzes for potential vulnerabilities and threats, and assists with prioritizing recommended countermeasures to defend the environment.

Mandiant also collects and reviews packet captures of network traffic from the ICS environment to validate the network diagram constructed in the workshop and to identify any unexpected or undesirable deviations from the intended design. This traffic is also analyzed for evidence of compromise or misconfiguration of the ICS network/system. Mandiant inspects the deployed security technology for vulnerabilities and other architectural risks, such as inappropriately configured firewalls, dual-homed control system devices, and unnecessary connectivity to the business network or the Internet.

NOTE: Findings are discussed at a generalized level to preserve the anonymity of our customers. This post presents a high-level overview and is meant to be an informative first stop for customers interested in common cyber security issues. For more information or to request Mandiant services, please visit our website.

Methodology: Mandiant Risk Rating System

This blog post leverages information from Mandiant ICS Healthchecks, which evaluate cyber security risk in organizations from multiple industries. The rating of critical and high security risk is based on the Mandiant Risk Rating System, which is determined by identifying the exploitability and the impact of a given issue, and cross-referencing the results (Figure 1).


Figure 1: Impact/exploitability graphic

One Third of Security Risks in ICS Environments Ranked High or Critical

We reviewed findings from all of our risk assessments and then categorized and ranked the reported risks as critical or high, medium, low, or informational (Figure 2). At least 33 percent of the security issues we found in ICS organizations were rated of high or critical risk. This means they were most likely to allow adversaries to readily gain control of target systems and potentially compromise other systems or networks, cause disruption of services, disclose unauthorized information, or result in other significant negative consequences. We suggest immediate remediation for critical risks, and quick action to remediate high security risks.


Figure 2: Risk assessment distribution

Most Common High and Critical Security Risks in ICS Environments

FireEye iSIGHT Intelligence organized the critical and high security risks identified during Mandiant ICS Healthchecks into nine unique categories (Table 1). The three most common were:

  • Vulnerabilities, Patches, and Updates (32 percent)
  • Identity and Access Management (25 percent)
  • Architecture and Network Segmentation (11 percent)

In most of these cases, basic security best practices would be enough to stop (or at least make it more difficult for) threat actors to target an organization's systems. The implications are vast because specialized malware or actors targeting infrastructure would likely look for these flaws first to exploit throughout the targeted attack lifecycle.


Table 1: Distribution of high and critical security risks in ICS environments

Top Three High and Critical Risks and Recommended Mitigations

Vulnerabilities, Patches, and Updates

Vulnerability, patch, and update management procedures enable organizations to secure off-the-shelf software, hardware, and firmware from known security threats. Known vulnerabilities in ICS environments can be leveraged by threat actors to access the network and move laterally to execute targeted attacks. The following common risks were observed during our engagements:

  • Infrequent procedures for patching and updating control systems:
    • We encountered organizations with no formal vulnerability and patch management programs.
  • Out-of-date firmware, hardware, and operating systems (OS), including:
    • Network devices and systems such as switches, firewalls, and routers.
    • Hardware equipment, including desktop computers, cameras, and programmable logic controllers (PLCs).
    • Unsupported legacy operating systems such as Windows Server 2003, XP, 2000, and NT 4.
  • Unaddressed known vulnerabilities in software applications and equipment where patches are available:
    • We observed outdated firewalls with up to 53 unaddressed vulnerabilities and switches with more than 200 vulnerabilities.
    • System management software that can be exploited using known open source tools.
  • Lack of test environments to analyze patches and updates before implementation.

Mitigations

  • Develop a comprehensive ICS Vulnerability Management Strategy and include procedures to implement patches and updates on key assets. More information is provided by the National Institute for Standards and Technology's (NIST) Guide for ICS Security NIST SP800-82.
  • When patches and updates are no longer provided for key infrastructure, choose one of the two following options:
    • Implement a security perimeter around affected assets, protected by, at minimum, a firewall (industrial protocol inspection/blocking if appropriate) for access control and traffic filtering.
    • Decommission legacy devices that might be exploited to gain access to the network, such as switches.
  • Set up development systems or labs that are representative of the running IT and ICS devices. These systems can often be built from existing spares along with the purchase or loan of additional licenses for human-machine interfaces (HMIs) and configuration software from the system vendor. A development system is an excellent platform to test changes and patches, and on which to perform vulnerability scans without risk to active systems.
Identity and Access Management

The second most common category of security issues identified was related to the flaws in or absence of best practices for handling passwords and credentials. Common weaknesses identified by Mandiant include:

  • Lack of multi-factor authentication for remote access and critical accounts:
    • Users were able to remotely access ICS environments from the corporate network without requiring multi-factor authentication.
  • Lack of a comprehensive and enforced password policy:
    • Weak passwords with insufficient length or complexity used for privileged accounts, ICS user accounts, and service accounts.
    • Passwords were not changed frequently.
    • Passwords were reused for multiple accounts.
  • Prominently displayed passwords:
    • Passwords were written on the chassis of devices.
  • Hard-coded and default credentials in applications and equipment:
    • Mandiant discovered Remote Terminal Units (RTUs) containing default credentials, which are commonly available on the Internet and in the device manuals.
    • A modem contained a backdoor account incorporated by the manufacturer.
  • Commonly used “administrator” accounts.
  • Use of shared credentials.

Mitigations

  • Implement two-factor authentication for all possible users, especially administrative accounts.
  • Avoid keeping written copies of passwords and, if necessary, secure them out of sight with limited access for only authorized users.
  • Enforce password policies that require strong passwords that are regularly modified and cannot be reused. More information is available from SANS.
  • Avoid common, easily guessed user account names such as "operator," "administrator," or "admin." Instead, use uniquely named user accounts for all access.
  • Require administrative users to log in with uniquely named user accounts with strong passwords, tied back to an individual person.
  • Avoid shared accounts when feasible. However, if present, they should be hardened using strong passwords that are stored in an encrypted password manager.
Network Segregation and Segmentation

Of the top three risks identified in this post, weaknesses in network segregation and segmentation are the most important. Lack of segregation from the corporate IT network and within the ICS network allows threat actors opportunities to launch remote attacks against key infrastructure by moving laterally from IT services to ICS environments. Furthermore, it increases the risk of commodity malware spreading to ICS networks where the malware could interact with operational assets. The main risks identified by Mandiant included:

  • Plant systems accessible from the corporate network, either directly or through bridge devices (connected to both networks), such as unused servers, HMIs, historians, or loosely configured shared firewalls. We also found:
    • Unfiltered access to plant servers from corporate networks through, for example, a historian communicating with the distributed control system (DCS).
    • Missing segmentation between ICS and corporate networks.
    • Vulnerabilities in bridge devices (e.g., outdated appliances running vulnerable OS) that can enable lateral movement between networks.
    • Business functions (e.g., data backups and anti-virus updates) running on shared control system networks.
  • Dual-homed systems, both servers and desktop computers.
  • Industrial networks connected directly to the internet.

Mitigations

  • Segment all access to ICS with a network Demilitarized Zone (DMZ), as recommended by both NIST SP 800-82 and IEC (Figure 3):
    • Restrict the number of ports, services, and protocols used to establish communications between the ICS and corporate networks to the least possible to reduce the attack surface.
    • Terminate incoming access for both regular and administrative users first in the DMZ, and then establish another session with connectivity into the ICS network.
    • Place servers (or mirrored servers) that provide ICS data to the corporate network in the DMZ.
    • Use firewalls to filter all network traffic entering or leaving the ICS.
    • Firewall rules should filter both incoming traffic from the corporate network and outgoing traffic from the ICS, and they should only allow the minimum required amount of traffic to pass.
  • Isolate the control networks from the internet. A separate network should be used for internet access through a DMZ, and at no time should a bridged connection be allowed between the two networks.
  • Ensure that independent, regularly patched firewalls are used to separate the corporate network from the DMZ and ICS network, and review firewall rulesets on a regular basis.
  • Identify and redirect any non-control system traffic traversing the industrial network.
  • Eliminate all dual-homed servers and hosts.


Figure 3: Reference architecture for segmentation of enterprise and control system networks

Additional Highlights

Additional common risks were identified from other categories, but with less frequency.

Network Management and Monitoring
  • We identified the lack of Network Security Monitoring, Intrusion Detection, and Intrusion Prevention in organizations, including missing endpoint malware protection, leaving unused ports active, and having limited visibility into ICS networks. We recommend the following best practices:
    • A comprehensive network security monitoring strategy should be defined and implemented at the ICS level as part of an overarching ICS security program. Special attention should be placed on monitoring network segments where external connectivity occurs:
  • Implement or increase centralized system and network logging to provide visibility across the entire enterprise (IT and ICS). Monitor logs for anomalous behavior. Consider implementing additional host or network-based security controls that generate alerts or reject traffic based on anomalous or suspicious behavior.
  • Install a centrally managed anti-malware solution on all ICS and ICS DMZ hosts. Ensure that signature and application updates are deployed in a timely manner.
  • Explore alternatives for the deployment of an advanced endpoint protection solution that provides detection/prevention for malware and malicious activities that do not rely on signature-based detection methods.
  • Develop procedures to identify and shut down network ports when not in use.
Misconfigurations in Firewall Rules

We identified weak firewall rules including "ANY-ANY" configurations, conflicting or overlapping rules, overly permissive conditions allowing access to administrative services, and lack of console connection timeouts. We recommend the following best practices for secure firewall configuration:

  • Filtering rules should only allow access from/to specific source/destination IP addresses and ports.
  • Filter rules should specify a specific network protocol.
  • ICMP filter rules should specify a specific message type.
  • Filter rules should drop network packets instead of rejecting them.
  • Filter rules should perform a specific action and not rely on a default action.
  • Administrative session timeout parameters should be set to terminate those sessions after a predetermined amount of time.
Cyber Security Governance Best Practices

We identified some organizations with limited or absent formal and comprehensive ICS security programs. We highly suggest organizations implement ICS security programs to prioritize the following recommendations:

  • Establish a formal ICS security program with a clearly defined owner, accountability, and governance structure. It should include:
    • Business expectations, policies, and technical standards for ICS security.
    • Guidance on proactive security controls (e.g., implementation of patches and updates, change management, or secure configurations).
    • Incident Response, Disaster Recovery, and Business Continuity plans.
    • ICS security awareness training plans.
  • Develop a Vulnerability Management Strategy following NIST SP800-82, including asset identification and inventory, risk assessment and analysis methodology (with prioritization of critical assets), remediation testing, and deployment guidelines.

Conclusion

This blog post presents a broad picture of the current risks facing industrial organizations as observed during Mandiant ICS Healthchecks. While the trends observed in this research align with risk areas commonly discussed in security conference talks and media reports, this blog draws from dozens of on-site assessments that hold real-life validity.

Our findings indicate that at least one third of the critical and high security risks in ICS are related to vulnerabilities, patches, and updates. Known vulnerabilities continue to represent significant challenges for ICS owners that must oversee the daily operation of thousands of assets in complex industrial environments. It is also relevant to highlight that some of the most common risks we identified could be mitigated with security best practices, such as enforcing a comprehensive password management policy or establishing detailed firewall rules. If you are interested in more information or to request Mandiant services, please visit our website.