Category Archives: bitcoin

JCry – A Ransomware written in Golang!

Estimated reading time: 4 minutes

For several months, QH Labs has been observing an upswing in ransomware activity. We found a new ransomware which is written in Go lang. Malware authors are finding it easy to write ransomware in Go lang rather than traditional programming languages.

Infection of Jcry ransomware starts with a compromised website.

As shown in the above image, malware author tries to impersonate users by pretending to be an update of Adobe flash player and download malware on the user’s machine. Fig 1. contains a part of javascript hosted on the compromised domain, which downloads a malicious file from the given URL. Whenever an impersonated user clicks on the Update button and executes a malicious file with the intention of updating the flash player, malware starts its execution.

Fig 1 : Part of malicious script.

Flow of Execution:

Technical Analysis:

Downloaded malware (flashplayer_install.exe) is Self-extracting archive. On execution, it will extract the below mentioned components in “Startup” directory to create its persistence.

Components:

  1. msg.vbs
  2. Enc.exe
  3. Dec.exe

Fig 2 : Extracted components and SFX instructions.

As mentioned in the above figure malware extract components and starts msg.vbs along with enc.exe(Encryptor)

msg.vbs:

This file is used to impersonate the user that, the system tried to update adobe flash player but access is denied for the user.

Fig 3 : Message shown by msg.vbs

Enc.exe (Encryptor):

This executable is responsible for file encryption and it is written in Go language.

Fig 4 : Go Build ID and library strings of Go Lang found in file.

On execution, it firstly checks for the existence of “personalKey.txt” file in the current directory, to determine that system is already infected or not. If the file exists then malware considers that the system is already infected and it terminates itself. As well as it deletes msg.vbs and Enc.exe with the help of decryptor file. During encryption, it uses the combination of AES and RSA algorithm. File encryption is performed using AES 128 bit algorithm with 16-byte initialization Vector in CBC mode. Hardcoded RSA public key is found in the enc.exe file which is later used to encrypt AES key.

Fig 5 : RSA PUBLIC KEY

 

Fig 6: Acquire Context for Crypto operations.

It encrypts the below listed 138 extension files.

“3dm, 3ds, 3g2, 3gp, 7z, ai, aif, apk, app, asf, asp, avi, b, bak, bin, bmp, c, cbr, cer, cfg, cfm, cgi, cpp, crx, cs, csr, css, csv, cue, dat, db, dbf, dcr, dds, deb, dem, der, dmg, dmp, doc, dtd, dwg, dxf, eps, fla, flv, fnt, fon, gam, ged, gif, gpx, gz, h, hqx, htm, ics, iff, iso, jar, jpg, js, jsp, key, kml, kmz, log, lua, m, m3u, m4a, m4v, max, mdb, mdf, mid, mim, mov, mp3, mp4, mpa, mpg, msg, msi, nes, obj, odt, otf, pct, pdb, pdf, php, pkg, pl, png, pps, ppt, ps, psd, py, rar, rm, rom, rpm, rss, rtf, sav, sdf, sh, sln, sql, srt, svg, swf, tar, tex, tga, thm, tif, tmp, ttf, txt, uue, vb, vcd, vcf, vob, wav, wma, wmv, wpd, wps, wsf, xlr, xls, xml, yuv, zip”

To speed up the encryption, it encrypts only 1MB data for files of size more than 1 MB. After successful file encryption it appends “.jcry” extension to the filename.

Fig 7:Encrypted files with jcry Extension.

After encryption of files, it deletes all shadow copies with the help of the below command.

                                                                  “vssadmin delete shadows /all”

and launch Dec.exe using Powershell command.

Fig 8: Vssadmin and PowerShell execution.

Dec.exe:

On execution of Dec.exe firstly it terminates and deletes enc.exe. Dec.exe is console application which asks the decryption key (RSA private key). After entering valid key it may decrypt encrypted files.

Fig 9 : Dec.exe.

It also drops ransom note on desktop location. To recover encrypted files it demands for 500$ as ransom and provides onion link (hxxp://kpx5wgcda7ezqjty.onion) where infected user will get private key after payment.

Fig 10: Ransom Note.

 

IOCs:

flashplayer_install.exe: c86c75804435efc380d7fc436e344898
Enc.exe : 5B640BE895C03F0D7F4E8AB7A1D82947
Dec.exe : 6B4ED5D3FDFEFA2A14635C177EA2C30D
Recovery Link: hxxp://kpx5wgcda7ezqjty.onion
Wallet Id: 1FKWhzAeNhsZ2JQuWjWsEeryR6TqLkKFUt

 

Prevention tips:

  1. Regularly take a backup of your important data in external drives like HDD, pen drive or Cloud storage.
  2. Install an antivirus and keep it updated.
  3. Keep your Operating System and software up-to-date.
  4. Never click on links or download attachments from any unknown or unwanted sources.

Subject Matter Expert:

Nagesh lathakar, Pratik Pachpor | Quick Heal Security Labs

The post JCry – A Ransomware written in Golang! appeared first on Seqrite Blog.

Cryptojacking Up 4,000% How You Can Block the Bad Guys

Cryptojacking RisingThink about it: In the course of your everyday activities — like grocery shopping or riding public transportation — the human body comes in contact with an infinite number of germs. In much the same way, as we go about our digital routines — like shopping, browsing, or watching videos — our devices can also pick up countless, undetectable malware or javascript that can infect our devices.

Which is why it’s possible that hackers may be using malware or script to siphon power from your computer — power they desperately need to fuel their cryptocurrency mining business.

What’s Cryptocurrency?

Whoa, let’s back up. What’s cryptocurrency and why would people rip off other people’s computer power to get it? Cryptocurrencies are virtual coins that have a real monetary value attached to them. Each crypto transaction is verified and added to the public ledger (also called a blockchain). The single public ledger can’t be changed without fulfilling certain conditions. These transactions are compiled by cryptocurrency miners who compete with one another by solving the complex mathematical equations attached to the exchange. Their reward for solving the equation is bitcoin, which in the crypto world can equal thousands of dollars.

Power Surge

Cryptojacking RisingHere’s the catch: To solve these complex equations and get to crypto gold, crypto miners need a lot more hardware power than the average user possesses. So, inserting malicious code into websites, apps, and ads — and hoping you click — allows malicious crypto miners to siphon power from other people’s computers without their consent.

While mining cryptocurrency can often be a harmless hobby when malware or site code is attached to drain unsuspecting users CPU power, it’s considered cryptojacking, and it’s becoming more common.

Are you feeling a bit vulnerable? You aren’t alone. According to the most recent McAfee Labs Threats Report, cryptojacking has grown more than 4,000% in the past year.

Have you been hit?

One sign that you’ve been affected is that your computer or smartphone may slow down or have more glitches than normal. Crypto mining code runs quietly in the background while you go about your everyday work or browsing and it can go undetected for a long time.

How to prevent cryptojacking

Be proactive. Your first line of defense against a malware attack is to use a comprehensive security solution on your family computers and to keep that software updated.

Cryptojacking Blocker. This new McAfee product zeroes in on the cryptojacking threat and helps prevent websites from mining for cryptocurrency (see graphic below). Cryptojacking Blocker is included in all McAfee suites that include McAfee WebAdvisor. Users can update their existing WebAdvisor software to get Cryptojacking Blocker or download WebAdvisor for free.

Cryptojacking Rising

Discuss it with your family. Cryptojacking is a wild concept to explain or discuss at the dinner table, but kids need to fully understand the digital landscape and their responsibility in it. Discuss their role in helping to keep the family safe online and the motives of the bad guys who are always lurking in the background.

Smart clicks. One way illicit crypto miners get to your PC is through malicious links sent in legitimate-looking emails. Be aware of this scam (and many others) and think before you click on any links sent via email.

Stick with the legit. If a website, an app, or pop-up looks suspicious, it could contain malware or javascript that instantly starts working (mining power) when you load a compromised web page. Stick with reputable sites and apps and be extra cautious with how you interact with pop-ups.

Install updates immediately. Be sure to keep all your system software up-to-date when alerted to do so. This will help close any security gaps that hackers can exploit.

Strong passwords. These little combinations are critical to your family’s digital safety and can’t be ignored. Create unique passwords for different accounts and be sure to change out those passwords periodically.

To stay on top of the latest consumer and security threats that could impact your family, be sure to listen to our podcast Hackable? And, like us on Facebook.

The post Cryptojacking Up 4,000% How You Can Block the Bad Guys appeared first on McAfee Blogs.