Crooks hoping to empty company bank accounts are calling up the firms' bean-counters to chase invoices packed with hidden malware.
Finance staff are tricked into opening the booby-trapped messages in phone calls from con men, who claim to have emailed in legit paperwork that needs urgent attention. The documents instead include a Trojan that, when activated on the victim's PC, hands control of the Windows machine to the swindlers over the internet.
The social-engineering tactic has been used against staff at French organisations by miscreants posing as employees or business associates of the targeted outfits, reports net security firm Symantec. The scam has been used to spread Shadesrat, a remote access Trojan.
According to Symantec, "the attacks are currently localised to French organisations" and their subsidiaries in Luxembourg, Romania and other nations. The thieves have been distributing the Trojan as bogus invoices since February, but only last month started phoning victims ahead of time to lure them into opening the malware-laden accounting paperwork.
By targeting finance staff, the hackers can infiltrate their computers and swipe corporate banking login credentials and other information crucial to carrying out subsequent fraud.
"The attacker is well prepared and has obviously obtained the email address and phone number of the victim prior to the attack," a blog post by researchers at the security firm explained. "The victims of these attacks generally tend to be accountants or employees working within the financial department of these organisations. Since handling invoices is something they would do on a regular basis, this lure has the potential to be quite convincing.
"It appears that the attacker’s motivation here is purely financial. Targeting employees who work with company finances likely provides access to sensitive company account information. These employees may also have the authority to facilitate transactions on behalf of the organisation; a valuable target if the attacker gains access to secure certificates that are required for online transactions or confidential bank account information."
The Shadesrat Trojan can be licensed from underground cybercrime forums for as little as $40 to $100 a year. The software nasty is "under active development and clearly shows no indication of going away any time soon", according to Symantec. ®