Story image

Nemucod serves nasty package: Ransomware and ad-clickers

22 Aug 2016

Just last week ESET reported on Nemucod shifting away from ransomware and downloading the ad-clicking malware Kovter instead. Now, it seems that the operators of the notorious downloader went a step further and are serving their victims the whole package – ransomware as well as ad-clickers.

As before, the targeted user receives an email with an infected attachment containing an executable .js file – the downloader. After unpacking and running it, it downloads five files at once. The first two are ad-clickers detected by ESET as Win32/Kovter and Win32/Boaxxe.

But that’s just the beginning, as the remaining three files have one very clear objective – to find the most valuable files on the computer and encrypt them. To run the ransomware, Nemucod installs a PHP interpreter and an additional PHP library (these two files are actually clean). Only after that a third file – detected by ESET as PHP/Filecoder.D – is downloaded and starts its malicious activities, using an encryption key hardcoded directly in the malware.

“AFTER THE RANSOMWARE HAS FINISHED WITH ENCRYPTION, NEMUCOD CREATES A TEXT FILE WITH A RANSOM DEMAND.”

The result? Files with one of about 120 extensions, including MS Office files, images, videos, sound files, and others, get encrypted and get the “.crypted” extension. After the ransomware has finished with encryption, Nemucod creates a text file with a ransom demand. In the end, the PHP interpreter, its library and the filecoder file are removed from the system.

Looking at the rest of the payload, Boaxxe is a remotely controlled backdoor that is able to download and execute files or install extensions to popular browsers such as Chrome and Firefox. On top of this, the trojan connects to a C&C server enabling its operator to misuse the infected machine as a proxy server, probably as a means for click-fraud or boosting traffic for selected websites.

Another interesting Nemucod activity was observed at the end of last week in Latin America. The downloader was delivering large amounts of Win32/Spy.Banker.ADEA to Brazilian users.

Article by Ondrej Kubovic blogger for We live security

Why SD-WAN is key for expanding businesses - SonicWall
One cost every organisation cannot compromise on is reliable and quick internet connection.
New threat rears its head in new malware report
Check Point’s researchers view Speakup as a significant threat, as it can be used to download and spread any malware.
Oracle updates enterprise blockchain platform
Oracle’s enterprise blockchain has been updated to include more capabilities to enhance development, integration, and deployment of customers’ new blockchain applications.
Used device market held back by lack of data security regulations
Mobile device users are sceptical about trading in their old device because they are concerned that data on those devices may be accessed or compromised after they hand it over.
Gartner names ExtraHop leader in network performance monitoring
ExtraHop provides enterprise cyber analytics that deliver security and performance from the inside out.
Symantec acquires zero trust innovator Luminate Security
Luminate’s Secure Access Cloud is supposedly natively constructed for a cloud-oriented, perimeter-less world.
Palo Alto releases new, feature-rich firewall
Palo Alto is calling it the ‘fastest-ever next-generation firewall’ with integrated cloud-based DNS Security service to stop attacks.
The right to be forgotten online could soon be forgotten
Despite bolstering free speech and access to information, the internet can be a double-edged sword, because that access to information goes both ways.