Introduction On 2016-02-01, the Sucuri blog reported a spike in compromised WordPress sites generating hidden iframes with malicious URLs [1]. By 2016-02-02, I started seeing exploit kit (EK) traffic related to this campaign [2]. Sucuri noted that "admedia" was a common string used in malicious URLs generated by these iframes. Because of that, some people (including me) use the term "admedia" when referring to traffic generated by this campaign. These "admedia" URLs act as a gate between the compromised website and the EK server. EK traffic associated with this campaign has generally sent TeslaCrypt ransomware. However, characteristics of this campaign have evolved since Sucuri's original blog post.
Other sites like the Malwarebytes blog have also documented this campaign [6]. Sites like Malwarebytes and DeepEnd Research have also documented most of these recent changes [7, 8]. Let's look at a recent Angler EK infection related to this "admedia" campaign. In today's example, the chain of events starts with a compromised Joomla site.
Today's infection On Wednesday 2016-02-17 at approximately 18:14 UTC, I got a full chain of events. The chain started with a compromised website that generated an admedia gate. The gate led to Angler EK. Finally, Angler EK delivered TeslaCrypt, and we saw some callback traffic from the malware.
Details How did the compromised website generate the admedia gate? It was caused by injected script. As the Sucuri blog already reported, each .js file returned by the compromised site had malicious script appended to it. In a case on 2016-02-15, I also saw the same type of script included in an HTML page from the compromised website [5]; however, today's traffic only shows injected script in the .js files.
Each example of injected script has a long string of hexadecimal code. Translate that string from hex to ASCII, and you'll find a URL for the admedia gate.
In the traffic, an HTTP GET request to the admedia gate is followed by an HTTP POST. The HTTP POST returns more obfuscated script. That script generates a URL for an Angler EK landing page. How can we check this? Notice the "eval" function highlighted in the image below of HTML text returned by the admedia gate.
Take that HTML text and put it in a text editor. Change the "eval" to "alert" and save that text to a separate HTML file.
Open your newly-saved HTML file in a browser, and you should see the Angler EK landing page URL appear in a pop-up alert.
Below are images of the Angler EK traffic from today's infection.
Final words So far, I've only seen TeslaCrypt from this admedia campaign. In fact, I've seen a whole lot of TeslaCrypt lately, with little other ransomware from EK traffic. For example, I last saw CryptoWall on 2016-02-05 [9]. Since then, I haven't noticed any CryptoWall. However, my field of view is currently limited, and there's plenty of information on other types of ransomware that's been making the rounds lately [10, 11, and 12 to name a few]. Have you seen any admedia Angler EK or similar activity? If so let us know in the comments section below. Traffic and malware for this ISC diary can be found here. --- References: [1] https://blog.sucuri.net/2016/02/massive-admedia-iframe-javascript-infection.html |
Brad 394 Posts ISC Handler Feb 18th 2016 |
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Feb 18th 2016 5 years ago |
Excellent write up Brad! We observed the same traffic-type as well today. Two admedia gate to Teslacrypt and one of them was to the same site you mentioned: summerspellman[.]com.
Appreciate the references and caps. These diary entries end up as exercises for our team --and me! |
Dover 1 Posts |
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Feb 18th 2016 5 years ago |
DoverMonkey,
Thanks for the kind words. Always nice to hear from others who are seeing the same indicators. - Brad |
Brad 394 Posts ISC Handler |
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Feb 18th 2016 5 years ago |
Great analysis! Couple days ago we got hit with the same malware through almost the exact same sequence of events. The malware held a lot of files hostage, but it was quickly contained and there was no lasting damage. Thank goodness for backups! Check out this malwr analysis. https://malwr.com/analysis/MDE2MTc1NDI0MjAwNDBlMWFjOTAwMTVkNThjZTUzNzM/
This is some nasty stuff. |
Chris 1 Posts |
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Feb 18th 2016 5 years ago |
Brad,
here are a couple of additional domain names used for the same purpose: img.sinyayamorda.info img.chernayamorda.info img.belayamorda.info img.zelenayamorda.info img.krasnayamorda.info Basically they mean "colored face" in Russian, hinting that these are probably frontends, i.e. "belayamorda" means "whiteface" in English, etc. |
Chris 1 Posts |
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Feb 18th 2016 5 years ago |
Thanks for the additional domains! @Chris, yeah, it's some nasty stuff, alright.
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Brad 394 Posts ISC Handler |
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Feb 18th 2016 5 years ago |
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