Skip to main content

PureLocker Ransomware-as-a-Service

First observed in October 2019, PureLocker is a ransomware tool believed to have been created by Golden Chickens, a malware-as-a-service (MaaS) provider affiliated with the Cobalt Group and FIN6 advanced persistent threats.

Threat ID:
CC-3290
Category:
ransomware
Threat Severity:
Medium
Threat Vector:
Published:
14 November 2019 12:00 AM
Report a cyber attack: call 0300 303 5222 or email [email protected]

Summary

First observed in October 2019, PureLocker is a ransomware tool believed to have been created by Golden Chickens, a malware-as-a-service (MaaS) provider affiliated with the Cobalt Group and FIN6 advanced persistent threats.

Threat details

Written in PureBasic, it is advertised through dark web forums as being able to target web and data servers.

At the time of publication, it is unclear how PureLocker is distributed, although there are unconfirmed reports indicating it is delivered disguised as a Crypto++ library using Golden Chickens' more_eggs backdoor.

When executed, PureLocker will perform several anti-analysis checks to ensure it is not running in a virtual environment, as well as to verify it was executed correctly. It then loads a secondary copy of ntdll.dll, likely in an attempt to evade common user-mode hooking detection mechanisms. If successful, it will perform further checks to confirm the system year is 2019 and that it has sufficient administrative rights, only proceeding to the nest stage if all these checks are confirmed. PureLocker uses a hybrid AES+RSA algorithm using hard-coded RSA key to encrypt files and will avoid encrypting executable files (EXE, DMG, etc.).

Remediation steps

Type Step

If a device 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.

To avoid becoming infected with ransomware, ensure that:

  • 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, anti-virus 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 based on the principle 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 affected device and 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 device).

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: 14 February 2020 2:55 pm