A new malware Campaign discovered using password-protected Microsoft Excel spreadsheets to deliver LimeRAT malware.

Security researchers from Mimecast discovered the attack campaign, uses an email method to deliver the read-only weaponized Microsoft Excel spreadsheets.

LimeRAT malware via Excel Spreadsheet

The Microsoft Office is one of the most popular tools, it’s popularity was abused by cybercriminals to deliver malware.

With this current campaign attacker used Excel file with password-protected, to open the file victims should enter the password and it is included in the social engineered email.

To decrypt the password-protected file victims need to enter the password “VelvetSweatshop“, once decrypted it onboards the malicious macros embedded.

The final payload is the LimeRAT malware, a malicious remote access trojan that gives the attacker complete access to the victim’s machine.

“In this specific attack, the cybercriminals also used a blend of other techniques in an attempt to fool anti-malware systems by encrypting the content of the spreadsheet hence hiding the exploit and payload,” researchers told.

The malware allows cybercriminals to personalize each payload with different attributes. Once it gets installed in the machine it fetches details such as operating system, CPU, geolocation (country), user, and other details.

The following are the payload capabilities that include Cryptocurrency miner, worm, keystroke logger, screen grabber, information stealer, and ransomware.

Mostly the LimeRAT malware distributed as an email attachment, malicious online advertisements, social engineering, software ‘cracks’.

It is one of the powerful RAT for windows machines it was coded in Visual Basic .NET, known for its anti-virus evasion techniques, anti-virtual machine features, small footprint, and encrypted communications.

Another interesting feature of the malware is the use of multiple ports for communication, which establishes redundancy for the communication channels. It’s communication with the C&C server encrypted using the AES algorithm.