Hackers update CryptXXX ransomware to scan networks

Version 3.1 of malware looks to lock up networked drives

A new strain of the CryptXXX ransomware has been upgraded to scan for network resources, security researchers have discovered.

According to IT security firm Proofpoint, the malware has been upgraded to version 3.100 and bypasses not only currently available decryption tools but also uses SMB (aka Server Message Block) to scan for available network resources and encrypt them. The ransomware also includes the StillerX information stealing DLL, a new payment portal and changed extensions of encrypted files.

The researchers noticed last week that a CryptXXX variant exhibited interesting scanning activity on port 445, which is used for SMB and is primarily associated with Microsoft Windows Domain and Active Directory infrastructure.

It was observed that infected machines were, in fact, scanning a subnet of their local area network (LAN) in search of MS Windows shared drives.

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"Further analysis demonstrated that this new version of CryptXXX was capable of finding shared resources on the network, enumerating files in every shared directory, and encrypting them one by one," said the researchers in a blog post.

The malware has also been updated to prevent decryption tools from retrieving data from encrypted files. It further monetises infections by downloading and installing a DLL file that acts as a credential-stealing module. Dubbed StillerX, the DLL appears to be fully-featured and targets the credentials of a wide range of applications from poker software to Cisco VPN credentials.

There is also an updated payment portal that has been made to look more "user-friendly". The portal connects to a website hosted on the dark web via an Onion Tor browser.

The firm said that because CryptXXX also includes robust information-stealing capabilities, multi-layered network and endpoint protection are also critical to prevent data exfiltration in case of infection.

"CryptXXX updates have appeared very quickly over the last month and, without an available decryption tool, users and organisations must focus on detection and prevention," said the firm.

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