Ransom malware attacks underscore limitations of anti-virus software

Ransom malware attacks underscore limitations of anti-virus software

Trail of destruction ...

CryptoLocker, CryptoWall, CryptoDefense, Dirty Decrypt, Critroni, CTB Locker, TorrentLocker, Cryptographic Locker. The first and most famous of those, CryptoLocker, might be gone but still the an army of clones keep coming, getting ever more sophisticated, targeting more file types and storage shares.

With no end in sight, is the security industry any nearer to neutralising the phenomenon of Russian ransomware?

Security firm Bromium reverse-engineered every example of this type of malware its engineers could find, inferring that the solution for smaller businesses most affected by these attacks might lie not with security products but with better backup strategies. This is either a positive message or a cry of despair depending on which way you choose to look at it.

After this year's fightback against CryptoLocker, the makers of ransomware have generally upped their game, returning with better defences to keep researchers at bay. So far it seems to be working.

It looked promising for a while. Researchers noticed that some ransom malware was contacting the C&C before carrying out encryption, which made it easy to detect block the action before damage was done. Eventually, malware authors reversed the order in which those events occured to close the vulnerability.

Earlier forms also used HTTP to communicate but now favour encrypted channels such as HTTPS/SSL and even the relatively slow and easy-to-detect TOR to better hide the back and forth between victim PC and C&C; domains are now hardcoded to simplify this design.

Despite some errors - implementing encryption is unforgiving for ciphers such as RSA - the competence of the crypto used is also getting better over time, said Bromium.

Most troubling of all is simply the number of file types targeted by the latest ransomware, which now goes after database, CAD files, archives, source code files, backups and even certificates as well as files connected to some password managers. The worst example of this is TorrentLocker which targets an extraordinary 200 files types, including some obscure ones users might assume are safe.

In Bromium's view, using anti-virus against this type of threat is like throwing a shoe at a charging bear but it can afford to say that, of course, because it doesn't sell such products.

"Crypto-ransomware lacks the subtlety of Trojan attacks that evade detection during infection, openly flaunting its compromise and demanding payment since antivirus is unable to reverse the process," echoed Bromium chief security architect, Rahul Kashyap.

"Crypto-ransomware is a particularly devious attack because of its potential to cause financial losses and irreparable damage to organisations that cannot access critical files."

With attackers and defenders dug in trench warfare, ransomware's likely evolution in 2015 will be to find easier ways get the programs on to target PCs. A possible route for this is is to swap phishing attacks (the traditional method) for techniques such as malverstising, an increasingly popular distribution channel. The story of ransomware going forward might be less about what users are infected with than the ease with which they come into contact with it.

Another development will be to target specific systems, the first example of which was a ransom attack that exploited a sofwtare flaw found only on Synology NAS drives.

As for home users, Techworld's advice is simple - When it comes to malware, Windows is a drying field that needs some Amish-style ploughing. Install Linux or, better still, buy a Chromebook, and leave Windows ransomware behind for good.

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Tags scamsBromium


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