Category Archives: Zero-Day Vulnerability

Report: Banking Trojans Accounted for More Than Half of All Malicious Payloads in Q4 2018

A new report found that banking Trojans accounted for more than half of all malicious payloads observed in the fourth quarter of 2018.

According to the “Proofpoint Quarterly Threat Report,” this threat dominated the cyber landscape at the end of 2018, constituting 56 percent of all malicious payloads Proofpoint researchers detected.

Several new families helped banking Trojans beat out other categories of malware, including downloaders, credential stealers and remote-access Trojans (RATs), which made up 17 percent, 17 percent and 8 percent of total threats, respectively. Ransomware was barely present in Q4 2018 after spiking and quickly declining in the previous two quarters.

That being said, it’s clear that threat actors preferred to use well-known banking malware over newcomers. For example, Emotet and its botnet-like capabilities accounted for 76 percent of banking Trojan activity in the quarter; taken together, Emotet, Ursnif and Panda Banker (aka Zeus Panda) made up 97 percent of banking Trojan detections for Q4 2018.

More Active and More Sophisticated

Proofpoint’s findings help illustrate how threat actors iterated their banking Trojan use in 2018. Check Point found evidence of this trend when it observed banking Trojans increase their global impact by 50 percent between February and June of last year. In fact, the Dorkbot and Ramnit families made it onto the security firm’s “Top 10 Most Wanted Malware” list for June 2018.

Banking Trojans have also grown in sophistication more generally over the past few years. In April 2017, for instance, Proofpoint observed a large email campaign exploiting a new zero-day vulnerability to deliver the Dridex banking Trojan.

Other banking malware, including QakBot, has added wormlike features that enable it to self-propagate through shared drives and removable media. All the while, many banking Trojans increasingly conduct fileless attacks as a way of evading detection. Cisco Talos observed one such fileless campaign involving Ursnif in January 2019.

How Security Professionals Can Defend Against Banking Trojans

Security professionals can help defend their organizations against banking Trojans by using artificial intelligence technologies to move beyond rule-based security. Organizations should also consider using a unified endpoint management solution that can monitor endpoints for suspicious behavior indicative of malware and automatically uninstall any infected applications.

The post Report: Banking Trojans Accounted for More Than Half of All Malicious Payloads in Q4 2018 appeared first on Security Intelligence.

Unpatched vCard Flaw Could Let Attackers Hack Your Windows PCs

A zero-day vulnerability has been discovered and reported in the Microsoft's Windows operating system that, under a certain scenario, could allow a remote attacker to execute arbitrary code on Windows machine. Discovered by security researcher John Page (@hyp3rlinx), the vulnerability was reported to the Microsoft security team through Trend Micro's Zero Day Initiative (ZDI) Program over 6

FireEye Uncovers CVE-2017-8759: Zero-Day Used in the Wild to Distribute FINSPY

FireEye recently detected a malicious Microsoft Office RTF document that leveraged CVE-2017-8759, a SOAP WSDL parser code injection vulnerability. This vulnerability allows a malicious actor to inject arbitrary code during the parsing of SOAP WSDL definition contents. FireEye analyzed a Microsoft Word document where attackers used the arbitrary code injection to download and execute a Visual Basic script that contained PowerShell commands.

FireEye shared the details of the vulnerability with Microsoft and has been coordinating public disclosure timed with the release of a patch to address the vulnerability and security guidance, which can be found here.

FireEye email, endpoint and network products detected the malicious documents.

Vulnerability Used to Target Russian Speakers

The malicious document, “Проект.doc” (MD5: fe5c4d6bb78e170abf5cf3741868ea4c), might have been used to target a Russian speaker. Upon successful exploitation of CVE-2017-8759, the document downloads multiple components (details follow), and eventually launches a FINSPY payload (MD5: a7b990d5f57b244dd17e9a937a41e7f5).

FINSPY malware, also reported as FinFisher or WingBird, is available for purchase as part of a “lawful intercept” capability. Based on this and previous use of FINSPY, we assess with moderate confidence that this malicious document was used by a nation-state to target a Russian-speaking entity for cyber espionage purposes. Additional detections by FireEye’s Dynamic Threat Intelligence system indicates that related activity, though potentially for a different client, might have occurred as early as July 2017.

CVE-2017-8759 WSDL Parser Code Injection

A code injection vulnerability exists in the WSDL parser module within the PrintClientProxy method (http://referencesource.microsoft.com/ - System.Runtime.Remoting/metadata/wsdlparser.cs,6111). The IsValidUrl does not perform correct validation if provided data that contains a CRLF sequence. This allows an attacker to inject and execute arbitrary code. A portion of the vulnerable code is shown in Figure 1.


Figure 1: Vulnerable WSDL Parser

When multiple address definitions are provided in a SOAP response, the code inserts the “//base.ConfigureProxy(this.GetType(),” string after the first address, commenting out the remaining addresses. However, if a CRLF sequence is in the additional addresses, the code following the CRLF will not be commented out. Figure 2 shows that due to lack validation of CRLF, a System.Diagnostics.Process.Start method call is injected. The generated code will be compiled by csc.exe of .NET framework, and loaded by the Office executables as a DLL.


Figure 2: SOAP definition VS Generated code

The In-the-Wild Attacks

The attacks that FireEye observed in the wild leveraged a Rich Text Format (RTF) document, similar to the CVE-2017-0199 documents we previously reported on. The malicious sampled contained an embedded SOAP monikers to facilitate exploitation (Figure 3).


Figure 3: SOAP Moniker

The payload retrieves the malicious SOAP WSDL definition from an attacker-controlled server. The WSDL parser, implemented in System.Runtime.Remoting.ni.dll of .NET framework, parses the content and generates a .cs source code at the working directory. The csc.exe of .NET framework then compiles the generated source code into a library, namely http[url path].dll. Microsoft Office then loads the library, completing the exploitation stage.  Figure 4 shows an example library loaded as a result of exploitation.


Figure 4: DLL loaded

Upon successful exploitation, the injected code creates a new process and leverages mshta.exe to retrieve a HTA script named “word.db” from the same server. The HTA script removes the source code, compiled DLL and the PDB files from disk and then downloads and executes the FINSPY malware named “left.jpg,” which in spite of the .jpg extension and “image/jpeg” content-type, is actually an executable. Figure 5 shows the details of the PCAP of this malware transfer.


Figure 5: Live requests

The malware will be placed at %appdata%\Microsoft\Windows\OfficeUpdte-KB[ 6 random numbers ].exe. Figure 6 shows the process create chain under Process Monitor.


Figure 6: Process Created Chain

The Malware

The “left.jpg” (md5: a7b990d5f57b244dd17e9a937a41e7f5) is a variant of FINSPY. It leverages heavily obfuscated code that employs a built-in virtual machine – among other anti-analysis techniques – to make reversing more difficult. As likely another unique anti-analysis technique, it parses its own full path and searches for the string representation of its own MD5 hash. Many resources, such as analysis tools and sandboxes, rename files/samples to their MD5 hash in order to ensure unique filenames. This variant runs with a mutex of "WininetStartupMutex0".

Conclusion

CVE-2017-8759 is the second zero-day vulnerability used to distribute FINSPY uncovered by FireEye in 2017. These exposures demonstrate the significant resources available to “lawful intercept” companies and their customers. Furthermore, FINSPY has been sold to multiple clients, suggesting the vulnerability was being used against other targets.

It is possible that CVE-2017-8759 was being used by additional actors. While we have not found evidence of this, the zero day being used to distribute FINSPY in April 2017, CVE-2017-0199 was simultaneously being used by a financially motivated actor. If the actors behind FINSPY obtained this vulnerability from the same source used previously, it is possible that source sold it to additional actors.

Acknowledgement

Thank you to Dhanesh Kizhakkinan, Joseph Reyes, FireEye Labs Team, FireEye FLARE Team and FireEye iSIGHT Intelligence for their contributions to this blog. We also thank everyone from the Microsoft Security Response Center (MSRC) who worked with us on this issue.

Acknowledgement of Attacks Leveraging Microsoft Zero-Day

FireEye recently detected malicious Microsoft Office RTF documents that leverage a previously undisclosed vulnerability. This vulnerability allows a malicious actor to execute a Visual Basic script when the user opens a document containing an embedded exploit. FireEye has observed several Office documents exploiting the vulnerability that download and execute malware payloads from different well-known malware families.

FireEye shared the details of the vulnerability with Microsoft and has been coordinating for several weeks public disclosure timed with the release of a patch by Microsoft to address the vulnerability. After recent public disclosure by another company, this blog serves to acknowledge FireEye’s awareness and coverage of these attacks.

FireEye email and network solutions detect the malicious documents as: Malware.Binary.Rtf.

Attack Scenario

The attack involves a threat actor emailing a Microsoft Word document to a targeted user with an embedded OLE2link object. When the user opens the document, winword.exe issues a HTTP request to a remote server to retrieve a malicious .hta file, which appears as a fake RTF file. The Microsoft HTA application loads and executes the malicious script. In both observed documents the malicious script terminated the winword.exe process, downloaded additional payload(s), and loaded a decoy document for the user to see. The original winword.exe process is terminated in order to hide a user prompt generated by the OLE2link.

The vulnerability is bypassing most mitigations; however, as noted above, FireEye email and network products detect the malicious documents. Microsoft Office users are recommended to apply the patch as soon as it is available. 

Acknowledgements

FLARE Team, FireEye Labs Team, FireEye iSIGHT Intelligence, and Microsoft Security Response Center (MSRC).