Security firm Armorize has detected a new variant of Drive By Cache Attack. The attack refers to the process of a user visiting an infected page and subsequently gets installed with malware, without his/her knowledge and without having him/her to click on or to agree to anything. The attack detected by Armorize relied on a different sequence of events. In this case, malicious scripts are used to locate the malware which is already sitting in the browser’s cache directory, before executing it. This so-called drive-by cache approach make attacks harder to detect because no attempt is made to download a file and write it to disk, a suspicion manoeuvre many security software packages are liable to detect. By bypassing this step dodgy sorts are more likely to slip their wares past security software undetected.
Example of the attack
It is difficult for desktop antivirus technologies to detect Drive-by downloads statically using signatures. Drive-by cache approach make attacks harder to detect it. Browser exploits usually exist in the form of scripts, for example javascripts or flash actionscripts. In Drive-By caching, a shellcode after being executed,doesn’t make an attempt to download a file and write it to disk. Instead, it locates the malware which is already sitting in the browser’s cache directory, and executes it. Behavior-based detection, on the other hand, is very effective for this type of threat. For drive-by downloads, the behavior is consistent and can be well defined. Below is a comparison of Drive by Download and Drive By Cache attack:
The full write-up of the attack, code analysis, and the concept are explained well at Armorize blog. With rise in cyber attacks and exploitation techniques, we will surely see some more interesting 0-days in the coming days.
