Mac malware uses Windows-style PDF camouflage ruse

Mac malware creators are adopting Windows malware camouflage trickery in a bid to trick users into running their malicious creations.

Boobytrapped PDF files have long been a problem for Windows users. The OSX/Revir-B Trojan reapplies this approach towards Mac fans, who may be less familiar with the ruse.

The malware payload is an Macintosh application file that poses as a PDF. If opened, the file presents a Chinese language document concerning the disputed Diaoyu (Senkaku) Islands. Both China and Japan claim sovereignty of the disputed territory.

While users are perusing the text the malware attempts to install a backdoor Trojan horse.

The malware was submitted to VirusTotal, possibly after the original author tested to see whether it was detected by security firms. VirusTotal routinely samples files submitted through its service to security firms, who have began analysing the code.

"This malware may be attempting to copy the technique implemented by Windows malware, which opens a PDF file containing a ".pdf.exe" extension and an accompanying PDF icon," according to virus analysts at net security firm F-Secure.

"The sample in our hands does not have an extension or an icon yet. However, there is another possibility … extension and icon could have been lost when the sample was submitted to us. If this is the case, this malware might be even stealthier than in Windows because the sample can use any extension it desires."

It may be that the malware was designed to be distributed via email but this is unclear.

Mistakes in the code means that the malware fails to execute, according to net security firm Sophos, adding that there is no doubt the file is malicious. ®