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Fiendish CryptoLocker ransomware survives hacktivists' takedown

Proper post-op analysis would have killed it for good, says ex-rozzer

An attempt by security researchers to take down command and control nodes associated with the infamous CryptoLocker malware appears to have been unsuccessful in its ultimate aim of putting the Bitcoin-hungry crooks behind the scam out of business.

Activists from the group Malware Must Die put together a list of scores of domains associated with communications channels for the malware, which encrypts files on infected machines before demanding a ransom of up to 2 BTC (worth just over $2,000 at the time of writing), before beginning a takedown operation on Sunday (1 December).

Most of the 138 targeted domains were suspended but failed to kill off CryptoLocker, which was quickly resurrected, according to anti-botnet firm Damballa.

Adrian Culley, a former Scotland Yard detective turned technical consultant at Damballa, said that the take-down effort might have been more successful with post-takedown analysis.

"It is no surprise that the announcements of the death of CryptoLocker appear to have been somewhat premature. An essential part of the process is post-takedown analysis, which may turn out to be a post-mortem, or a triage of the zombie remnants of a botnet, or may indeed confirm that the botnet is very much still alive and kicking."

"It is essential to undertake this analysis post any sinkholing activity,” continued Culley, “which does appear to have happened in this instance. CryptoLocker appears to have the same resilience as many other C&C based attacks.”

“Efficient post-mortems lead to better surgery, and this is just as true of botnet remediation as it is medically," he added.

CryptoLocker normally arrives in email as an executable file disguised as a PDF, packed into a .zip attachment. A spam run targeting millions of UK consumers prompted a warning from the UK National Crime Agency last month. For now, at least, only Windows machines can be infected by the malware.

If it successful executes, CryptoLocker encrypts the contents of a hard drive and any connected LAN drives before demanding payment for a private key needed to decrypt the data. ®

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