FriedEx RDP Ransomware

FriedEx, also known as Bitpaymer, is a ransomware tool that targets exposed Remote Desktop Protocol (RDP) endpoints. First observed in July 2017, it is believed to have been created by the attackers responsible for the Necurs botnet and Dridex trojan.

Threat ID:: CC-2010
Category:: Ransomware
Threat Severity:: Medium
Threat Vector:
Published:: 1 February 2018 12:00 AM

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

This content has been archived

This article no longer conforms to NHS Digital's standards for cyber alerts, and may contain outdated or inaccurate information. Use of this information contained in this page is at your own risk

Summary

Threat details

The attackers using FriedEX appear to be far more involved in the infection process than most malware operators. They search for high-profile targets before manually performing the brute-force attack once an exposed RDP server is found.They then traverse the network and attempt to access further systems. It should also be noted that FriedEx has been delivered by phishing emails, malvertising campaigns and potentially unwanted applications.

Files are encrypted using a randomly generated RC4 key, that is itself then encrypted with a hardcoded 1024-bit RCA key, before being appended with the extension .locked. Ransom notes are then dropped in each folder which detail how the device was compromised and demanding over 50 BitCoins in payment. This large ransom appears to compensate for the greater amount of effort and smaller group of targets.

FriedEx shares several anti-detection features with Dridex. It uses encrypted strings and the registry keys are retrieved by hashing, making it difficult to identify the malware.

Remediation steps

Type	Step
	If RDP is not used then ensure port 3389 (TCP/UDP) is blocked at your internet firewall. If RDP is used: Ensure only authorised users are granted RDP permissions. Ensure authorised users have a strong password. Protect RDP connections with multifactor authentication. Only allow RDP to run through VPN connections. 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. 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, 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. Additionally, a number of open-source tools are available that are able to manually remove FriedEx.

Type

Step

If RDP is not used then ensure port 3389 (TCP/UDP) is blocked at your internet firewall. If RDP is used:

Ensure only authorised users are granted RDP permissions.
Ensure authorised users have a strong password.
Protect RDP connections with multifactor authentication.
Only allow RDP to run through VPN connections.

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.

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, 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.

Additionally, a number of open-source tools are available that are able to manually remove FriedEx.

Last edited: 17 February 2020 12:43 pm