Filecoder Ransomware

Filecoder ransomware has been seen targeting Irish computer users via a faked EIR (an Irish Telecommunications company) email. The email informs the user that they have a invoice that they need to pay and that they can download a copy of the invoice via a

link provided. Once the link is opened, a zip file containing the ransomware will be downloaded.
Filecoder encrypts files and asks you to pay a ransom to the attacker in order to get access to the decryption service.

Filecoder has been around since before July 2013 and has seen many variants effecting both Windows and Mac as well as using different techniques used to encrypt the user’s files.
Remediation

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.

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.

Affected Platforms