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Locky ransomware – for SMEs ransom extortion is always about weak backup

John E Dunn | March 16, 2016
'Locky' is a new family of ransomware first noticed in February when the spam used to spread it started being picked up in filters used by security vendors to spot threats.

'Locky' is a new family of ransomware first noticed in February when the spam used to spread it started being picked up in filters used by security vendors to spot threats. It's early days for Locky but in terms of the size of this campaign it appears to be second only to the current king of ransomware, CryptoWall, which Computerworld has written about on several occasions since it appeared in 2014.

First, spam is not the same as an infection, which is the point at which ransomware creates victims. It's important to state this because while Locky is undoubtedly a serious threat none of the firms that have commented on it, Trustwave and Fortinet, actually knows how successful it has been. Second, judging from the type of attachment campaign chosen by Locky, the target is SMEs, the target market that ransomware authors have honed in on as the most likely to pay up.

A BBC news story this week made the sudden surge in spam sounds like a mortal threat but there is always a trade-off in terms for any ransomware gang. Sending out large volumes of spam draws attention in ways that allows antivirus vendor to counter and shorten its window of opportunity. The traditional method for ransomware has been to sneak in below this detection system by targeting only specific sectors or countries or simply using techniques that are less noisy than spam to distribute malware.

The decision to use spam almost certainly means that Locky will come and go quite quickly, at least in this version. By the end of this week every major AV vendor will detect it. As Trustwave points out, businesses can also counter its distribution MO by blocking inbound attachments embedding Javascript or, less conveniently, blocking Office documents that have macros enabled. Beyond that, as ever with ransomware, it should be about having backup and the ability to respond to an outbreak by rapidly isolating infected systems.

Locky ransomware - the catch

Ransomware criminals persist because, whisper it, they know perfectly well that even comprehensive backups are not always enough.

The evidence is in the growing number of reports of SMEs, including some quite large ones, that have to resort to paying ransoms. The number admitting they've done this has grown to such an extent there doesn't even seem ot be much stigma about paying up. The circumstances are not always clear but a consistent anecdotal theme is that the killer is not that backups are not available but that reinstating them from or to servers could means days or even weeks of downtime. Paying a ransom of around $1,000 in Bitcoins is not strictly necessary so much as quicker and considerably cheaper.

 

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