Fiendish CryptoLocker ransomware: Whatever you do, don't PAY
Create remote backups before infection, advise infosec bods
'It may be possible to recover previous versions of the encrypted files'
The may be some hope of recovering previous versions of encrypted files but it's far better to avoid infection in the first place.
"In some cases, it may be possible to recover previous versions of the encrypted files using System Restore or other recovery software used to obtain 'shadow copies' of files," according to an advisory by anti-virus firm Malwarebytes.
More detailed advice on how some files might be recovered from infected machines can be found on borked PC advice website Bleeping Computer.
Another write-up of the threat can be found in a blog post by Trend Micro here.
Malwarebytes, Sophos (more info here) and other firms have added detection for strains of CryptoLocker to their antivirus products as well as blocking sites associated with the malware: factors that ought to provide some defence against infections taking hold.
However, antivirus technology can't help in recovering encrypted files post-infection.
The appearance of CryptoLocker reinforces the need to regularly back up personal data files. And local backups alone may not be enough. In some cases CryptoLocker may even attempt to attack backups located on a network drive connected to an infected PC. For this reason, a belt-and-braces approach featuring non-local and cloud-based backups becomes a sensible option.
Security experts agree that regular data backups are the best safeguard against potential calamity in the face of the threat.
Fabio Assolini, a senior security researcher at Kaspersky Lab, writes in a Twitter update."It's not possible to recover the files encrypted by CryptoLocker. It's not a good idea pay the ransom, backup is your friend."
Christopher Boyd, a senior threat researcher at ThreatTrack Security, concurred that recovery from backups is the best option: "There are only two real options (neither of which are particularly great).
"You can remove the virus but lose your files (unless you have them backed up), or pay the bad guys with a credit card to get the unlock code (assuming there even is one) to recover the locked data, then - one would assume - attempt to get the money back. Due to the potential complexity of the infection, email exchanges or even remote support may not be an ideal way to try to fix the problem."
A detailed discussion of the malware that took place around the time it first surfaced – in early September – can be found on a forum dedicated to kernel developers here. ®