AVCrypt Ransomware

AVCrypt is a new malware which may be a wiper or ransomware. AVCrypt has been observed targeting Anti Virus (AV) software.

Threat ID:: CC-2187
Category:
Threat Severity:: Medium
Threat Vector:
Published:: 28 March 2018 12:00 AM

Report a cyber attack: call 0300 303 5222 or email [email protected]

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Summary

AVCrypt is a new malware which may be a wiper or ransomware. AVCrypt has been observed targeting Anti Virus (AV) software.

Affected platforms

The following platforms are known to be affected:

Microsoft Windows

Microsoft Windows all Platforms

Threat details

The malware delivers a text file which contains a suspected ransom note. This file [+HOW_TO_UNLOCK.txt] contains only the text ‘lol n’ - there are no demands.

Affecting Windows platforms including Windows Defender, AVCrypt aims to delete Windows services to corrupt the operation of the system. The malware is capable of making system changes such as encrypting or deleting files and attempting to remove AV on targeted machines.

AV Crypt will sit stationary for a short time period after the initial infection allowing access to an integrated TOR client, this accesses bxp44w3qwwrmuupc[.]onion, a C2 server. At this point the attempted removal of security software is seen.

The malware is seen to scan and encrypt the device's documents adding a '+' to the front of the file name - e.g. 'Cake Recipe' goes to '+Cake Recipe'.

Remediation steps

Type	Step
	If a computer on your network becomes infected with ransomware it will begin encrypting local machine files and files on any network the logged-in user has permission to access. For system administration accounts this may include backup storage locations. A robust program of education and awareness training is delivered to users to ensure they don’t open attachments or follow links within unsolicited emails. All operating systems, antivirus and other security products are kept up to date. All day to day computer activities such as email and internet are performed using non-administrative accounts and that permissions are always assigned on the basis of least privilege. Your organisation adopts a holistic all round approach to Cyber Security as advocated by the 10 Steps To Cyber Security. Identifying the source of infection: Identifying the infected machine and unplugging / disconnecting or quarantining it from the network is essential to damage limitation. Users should immediately report infections to their IT support provider, disconnect their network cable and power the computer down. File auditing should be enabled and file server logs should be monitored to detect signs of unauthorised encryption and allow the source of encryption to be identified (i.e. the infected PC). To limit the damage of ransomware and enable recovery: All critical data must be backed up, and these backups must be sufficiently protected/kept out of reach of ransomware. Multiple backups should be created including at least one off-network backup (e.g. to tape). The only guaranteed way to recover from a ransomware infection is to restore all affected files from their most recent backup.

Type

Step

If a computer on your network becomes infected with ransomware it will begin encrypting local machine files and files on any network the logged-in user has permission to access. For system administration accounts this may include backup storage locations.
A robust program of education and awareness training is delivered to users to ensure they don’t open attachments or follow links within unsolicited emails.
All operating systems, antivirus and other security products are kept up to date.
All day to day computer activities such as email and internet are performed using non-administrative accounts and that permissions are always assigned on the basis of least privilege.
Your organisation adopts a holistic all round approach to Cyber Security as advocated by the 10 Steps To Cyber Security.

Identifying the source of infection:

Identifying the infected machine and unplugging / disconnecting or quarantining it from the network is essential to damage limitation.

Users should immediately report infections to their IT support provider, disconnect their network cable and power the computer down.
File auditing should be enabled and file server logs should be monitored to detect signs of unauthorised encryption and allow the source of encryption to be identified (i.e. the infected PC).

To limit the damage of ransomware and enable recovery:

All critical data must be backed up, and these backups must be sufficiently protected/kept out of reach of ransomware.

Multiple backups should be created including at least one off-network backup (e.g. to tape).

The only guaranteed way to recover from a ransomware infection is to restore all affected files from their most recent backup.

Last edited: 17 February 2020 12:38 pm