Technologies advance with time, and so is the case with Instant Messengers. Not long ago, people were happy sending text messages. Then VoIP came along and changed the scene. Soon after IM vendors embraced it. Many IM clients are now VoIP enabled. As soon as VoIP started going deeper into the mainstream, security researchers warned of related issues. One issue was abuse with spam, usually referred to as SPIT. Wikipedia states SPIT is “as-yet-nonexistent problem“. As VoIP is getting more popular the scenario is changing fast, this “as-yet-nonexistent problem” is slowly but surely emerging. The following images shows a real-world VoIP spam over Skype.

The image shows a typical spam prospect. The spammer starts a conference call with some random users and starts playing the spam message. This process is most likely not manual but automated with bots.

Use and abuse are two sides of the same coin and this technology is no exception. All major IM providers are giving away SDKs to develop add-ons. However these SDKs also lower the bar for spammers to develop bots. We have witnessed the same with the ongoing development around Skype malware.

The image below shows the assembly code for the loop which is used by Skype malware to search for users. You will notice the “SEARCH USERS” Skype APIs:

The malware actually uses more of these. The image below will highlight those:

These APIs are part of Skype SDK and are documented by skype. It is just a matter of time before we start seeing bots, in the wild build on top of IM SDKs provided by the vendors. We advise users to be aware of this developing attack vector. McAfee Avert Labs is prepared for this battle!!