Zorab Ransomware

Zorab is newly-observed ransomware that is disguised as a decryption tool for STOP (also known as Djvu) ransomware, but actually performs a further encryption on affected files.

Threat ID:: CC-3500
Category:: Ransomware
Threat Severity:: Low
Threat Vector:
Published:: 11 June 2020 12:00 AM

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

Summary

Zorab is newly-observed ransomware that is disguised as a decryption tool for STOP (also known as Djvu) ransomware, but actually performs a further encryption on affected files.

Affected platforms

The following platforms are known to be affected:

Microsoft Windows

Microsoft Windows - All versions

Threat details

Zorab is unwittingly downloaded by users who cannot afford or do not want to pay a ransom to recover their files, so search for a decryption tool.

When the fake decryption tool is run it first asks the user to input their STOP ransomware details. When these are submitted the Zorab ransomware executable is extracted to the %Temp% folder. This will then encrypt the user's files and append the .ZRB extension to filenames. A ransom note is saved in each folder containing encrypted files, that asks the affected user to contact the threat actors.

Remediation steps

Type	Step
	If a device on your network becomes infected with ransomware it will begin encrypting files, which may also include remote files on network locations. The only guaranteed way to recover from a ransomware infection is to restore all affected files from their most recent backup. To reduce the likelihood of infection by ransomware, NHS Digital advises that: Secure configurations are applied to all devices. Security updates are applied at the earliest opportunity. Tamper protection settings in security products are enabled where available. Obsolete platforms are segregated from the rest of the network. IT usage policies are reinforced by regular training to ensure all users know not to open unsolicited links or attachments. Multi-factor authentication (MFA) and lockout policies are used where practicable, especially for administrative accounts. Administrative accounts are only used for necessary purposes. Remote administration services use strongly encrypted protocols and only accept connections from authorised users or locations. Systems are continuously monitored, and unusual activity is investigated, so that a compromise of the network can be detected as early as possible. Please note that NCSC maintains guidance for securely configuring a wide range of end user device (EUD) platforms. For further details refer to their end user device security guidance pages. To limit the impact of a ransomware infection, NHS Digital advises that: Critical data is frequently saved in multiple backup locations. At least one backup is kept offline at any time (separated from live systems). Backups and incident recovery plans are tested to ensure that data can be restored when needed. User account permissions for modifying data are regularly reviewed and restricted to the minimum necessary. Infected systems are disconnected from the network and powered down as soon as practicable. Any user account credentials that may have been compromised should be reset on a clean device. Where infected systems cannot be quarantined with confidence, then an affected organisation should disconnect from national networks to limit propagation.

Type

Step

If a device on your network becomes infected with ransomware it will begin encrypting files, which may also include remote files on network locations. The only guaranteed way to recover from a ransomware infection is to restore all affected files from their most recent backup.

To reduce the likelihood of infection by ransomware, NHS Digital advises that:

Secure configurations are applied to all devices.
Security updates are applied at the earliest opportunity.
Tamper protection settings in security products are enabled where available.
Obsolete platforms are segregated from the rest of the network.
IT usage policies are reinforced by regular training to ensure all users know not to open unsolicited links or attachments.
Multi-factor authentication (MFA) and lockout policies are used where practicable, especially for administrative accounts.
Administrative accounts are only used for necessary purposes.
Remote administration services use strongly encrypted protocols and only accept connections from authorised users or locations.
Systems are continuously monitored, and unusual activity is investigated, so that a compromise of the network can be detected as early as possible.

Please note that NCSC maintains guidance for securely configuring a wide range of end user device (EUD) platforms. For further details refer to their end user device security guidance pages.

To limit the impact of a ransomware infection, NHS Digital advises that:

Critical data is frequently saved in multiple backup locations.
At least one backup is kept offline at any time (separated from live systems).
Backups and incident recovery plans are tested to ensure that data can be restored when needed.
User account permissions for modifying data are regularly reviewed and restricted to the minimum necessary.
Infected systems are disconnected from the network and powered down as soon as practicable.
Any user account credentials that may have been compromised should be reset on a clean device.
Where infected systems cannot be quarantined with confidence, then an affected organisation should disconnect from national networks to limit propagation.

Indicators of compromise

Main indicators

SHA256 File Hashes

1abf41be04801cfc3478502127abc47c2d84253ab659d576e5c02cc0b716c782

Filenames

Decryptor Djvu mlagham.exe
--DECRYPT--ZORAB.txt.ZRB
%Temp%\crab.exe

Email Addresses

zorab28@protonmail[.]com

Last edited: 29 June 2021 12:01 pm