A Look Behind The Skype Malvertising Campaign

Sub-domain on SourceForge redirects to Flash Pack Exploit Kit

We have talked about SourceForge before on this blog, in particular when they were associated with bundled software.

This time around, we are going to take a look at an infected sub-domain hosted on SourceForge responsible for a drive-by download attack.

Redirection overview


The first redirection is located within a JavaScript file:


This calls to stat-count.dnsdynamic.com a domain previously identified as a source of malicious activity. This one is no different:


You may recognize the URL landing for the Flash Pack Exploit Kit. There is an interesting series of redirections and here’s the flow:

hxxp://yi4dtvjlvfvos6ffvnxxklf.alobakkal.net/index.php?w=anM9MSZuc29sbHZpej1qdmRhY2FoJnRpbWU9MTQwODI1MDE1NDI5NzcyNDgyNiZzcmM9MjIwJnN1cmw9YW50aWRvci5uZXQmc3BvcnQ9ODAma2V5PTgxQkZCQUJFJnN1cmk9L2FkL3NvdXJjZWZvcmdlL2FkXzA5Ny8xNTkyMDE0NjYv hxxp://yi4dtvjlvfvos6ffvnxxklf622053f032259300cb84bd8aa84eae65a.alobakkal.net/index2.php hxxp://yi4dtvjlvfvos6ffvnxxklf.alobakkal.net/coder/index.php hxxp://yi4dtvjlvfvos6ffvnxxklf.alobakkal.net/coder/js/swfobject.js hxxp://yi4dtvjlvfvos6ffvnxxklf.alobakkal.net/coder/client_do.swf

The last URL is a Flash file, VT detection here.


Another redirection caught our attention:


A Flash file with a peculiar name for its classes:




The payload (VT results) is detected by Malwarebytes Anti-Malware as Trojan.Agent.ED.

The video below shows the exploit happening and getting blocked by our Malwarebytes Anti-Exploit:


We have spotted similar redirections to the Flash Pack exploit kit in other popular sites as well. Whether is it part of a larger campaign is hard to say but it is particularly active at the moment.

Drive-by download attacks are the number one vector for malware infections. Legitimate websites often fall victim to malicious injections stealing incoming traffic and sending it to booby-trapped pages. Within seconds, an unpatched computer could get infected with a nasty piece of malware.

On top of keeping your computer up-to-date and running the latest versions of antivirus and anti-malware software, adding an additional layer of protection against exploits greatly reduces the attack surface the bad guys are banking on.



Jérôme Segura

Principal Threat Researcher