Pierluigi Paganini September 21, 2016

Google has removed from the Google Play store four apps trojanized with the Overseer malware to target overseas travelers seeking embassy information.

Google has removed from the official Google Play store four trojanized apps that targeted overseas travelers seeking embassy information and news for specific European countries.

Three apps were named “Embassy”, “European News”, “Russian News,” a fourth one was using Cyrillic. I personally consider the threat as severe because who is behind the Overseer malware is targeting foreign travelers, especially enterprise executives that had downloaded the Embassy app during their business travels.

The malicious apps were spotted in late July by security experts from the Lookout’s Security Research and Response Team, which called the threat Overseer. The mobile apps were developed to gather user information from their Android devices, including contacts, email, GPS data, device data (i.e. Model, device ID, device rooted or not).

Lookout malware experts reported the presence of the Overseer malware in the apps of the Google Play on Aug. 4, Bit G promptly removed them from the store.

The Overseer apps were downloaded 10,000 times via Google Play.

“Through close collaboration with an enterprise customer, Lookout identified Overseer, a piece of spyware we found in four apps live on the Google Play store. One of the apps was an Embassy search tool intended to help travelers find embassies abroad. The malware was also injected as a trojan in Russian and European News applications for Android.” reported a blog post published by Lookout.

The threat actors behind the app used command-and-control servers located on Facebook’s Parse Server, hosted on Amazon Web Services. This technical choice allows Vxers to avoid malicious traffic detection.

“By using the Facebook and Amazon services, the spyware makes use of HTTPS and a C&C residing in the United States on a popular cloud service. This allows it to remain hidden because it doesn’t cause Overseer’s network traffic to stand out and could potentially present a challenge for traditional network-based IDS solutions to detect,” continues the post.

Once the Overseer malware has infected the Android mobile device it would contact the C&C server to receive instructions or malicious payloads and exploits to download and execute.

“Devices infected with Overseer periodically beacon to the api.parse.com domain, checking whether there are any outstanding commands the attacker wants to run. Depending on the response, the malware is capable of exfiltrating a significant amount of information from an infected device. These communications are all encrypted over the wire, which hides the traffic from network security solutions.” reads the analysis published by Lookout.

The researchers from Lookout discovered more apps in the Play Store also infected with the Overseer malware, a circumstance that led them to believe that these apps were created for the purpose of distributing the Overseer malware.

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Pierluigi Paganini

(Security Affairs – Overseer malware, Android)