In August 2009, Arbor Networks researcher Jose Nazario uncovered a botnet using Twitter as a command and control mechanism. Since then, other examples of attackers taking advantage of Web 2.0 sites have continued to sporadically pop up.
The tactic remains quite rare, but there are a number of reasons why attackers may increasingly look to such sites for hosting purposes.
"Attackers are taking advantage of the ability with these social networking platforms to hide their activities in plain site," a spokesperson for EMC's RSA security division told eWEEK. "Because of the millions of social networking users, cyber-criminals can simply blend their illegal activities and content and get lost in the crowd. And they can do so using encryption to cover their tracks."
In a lengthy analysis, RSA's FraudAction Research Lab examined how attackers used an unidentified social networking site to send commands to a Brazilian banker Trojan.
According to RSA,
"This is how it worked:1. The cybercriminal behind the crimeware set up a bogus profile under the name of "Ana Maria", and entered the crimeware's encrypted configuration settings as text uploaded to the profile. 2. After infecting a user's machine, and installing itself on it, the malware searched the profile for the string EIOWJE (underlined in the above screenshot). The string signified the starting point of the malware's configuration instructions. 3. All the encrypted commands following the EIOWJE string were decrypted by the malware and executed on the infected computer."
The method described above "allows the cyber-criminal to issue encrypted commands without renting a dedicated, bulletproof server or registering a domain for the malware's communication points," RSA researchers noted in the blog post.
"We do see the trend continuing because social networks offer free and resilient platforms to host this information," the RSA spokesperson told eWEEK. "The postings themselves are difficult to detect ... on the part of the social networking operators and also difficult to detect from the user computer side. A user could have an infected computer as part of a botnet and their security monitoring software may still never detect any illicit activity.
"The infected PC would be communicating to an account that is hosted on a legitimate social network rather than with a botnet mother ship server," the spokesperson continued. "Even if that social network account gets taken down, it's still much faster and easier for the cyber-criminal to set up new accounts for free and evade detection of that account rather than having the botnet mother ship server end up on an IP address blacklist."
The good news for users is that, once detected, the removal of this type of command and control points is relatively simple and quick.