Linux 'Hand of Thief ' bank Trojan is not viable malware, says RSA

Protoype's capabilities oversold

The 'Hand of Thief' (HoT) Linux banking Trojan that was offered for sale on the criminal underground this summer is a primitive "prototype" that poses little real threat to users of the OS, a new analysis by RSA has reported.

Having tested the programme, it now looks as if the individual offering it for sale on Russian crime forums at a premium price was doing an ambitious sales job on its imagined capabilities.

The firm's researchers fired up HoT's Windows bot builder programme, using it to create a working binary for test purposes. Immediately, they started noticing inefficiencies in its design such as the need to generate a new binary every time basic configuration changes were made.

Under Fedora 19, while HoT was able to infect the machine but also caused the Firefox Linux browser to crash and freeze, and turned out to capture unnecessary amounts of data that would have complicated the task of stealing credentials.

Under Ubuntu 12.04, HoT failed to work at all thanks to this distribution's ptrace scope protection. Even disabling this made little difference as the browser suffered similar crashes and the malware proved unable to capture anything.

A more general weakness was the lack of commercial exploit packs for Linux that are commonly used to automate drive-by campaigns against Windows users, RSA said.

The overall impression is of a piece of malware that fails to live up its marketing hype.

"Hand of Thief has come to the cybercrime underground at a time when commercial Trojans are high in demand, stirring some excitement amongst criminals," said RSA's Yotam Gottesman, who conducted the analysis.

"Although it initially appeared to be a compelling new Trojan entrant, RSA's in-depth analysis of the code proves it is a prototype more than true commercially viable malware, crashing the browsers on the infected machines and displaying overall inability to properly grab data," he said.

The malware could also easily be removed from an infected Linux system simply by deleting files dropped during install.

"Hand of Thief's developer claims that he is in the final stages of implementing a web-injections mechanism, but since the Form grabber he designed is not functional on the browsers he claims to have tested, the injections are not very likely to work either."

Linux malware, of course, is incredibly rare and the dramatic-sounding Hand of Thief malware would have been the first designed to attack online bank access on the OS.

HoT was first noticed for sale earlier this summer on a Russian forum for $2,000 (£1,250) a pop. Its appearance was taken as a sign that despite its small and generally specialised user base malware writers might be warming up to the eccentric idea that Linux was a platform worth attacking.

To date, HoT has not been detected in real-world attacks.

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