As Discord is gaining extreme popularity among online user communities, with 150 million people using it as of 2021, hackers turn their sights to this chat, VoIP, and digital distribution platform. The possible attack surface is vast and promising, allowing threat actors to abuse Discord for malware distribution and other nefarious actions. 

Recently, security researchers have revealed yet another malware exploiting the trending Discord attack kill chain. Particularly, hackers abuse the Discord CND (Content Distribution Network) to drop a plea of remote access Trojans with the help of a novel SYK crypter.

Detect SYK Crypter

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Suspicious Syk Crypter Execution with Powershell (via cmdline)

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SYK Crypter Attack Chain

According to the research by Morphisec, SYK Crypter operators haven’t missed a chance to leverage a popular Discord attack chain for malware distribution. In May 2022, security experts reported multiple SYK Crypter infections conducted with the help of Discord CND. 

Particularly, the attack starts with a phishing email holding a malicious file attached. The file is masquerading as a legitimate purchase order, but if opened, it triggers the infection chain. At the first stage, DNetLoader lands onto the victim’s machine to connect to a hardcoded Discord CND endpoint and download the encrypted files. Further, the SYK crypter comes into action, decrypting the final payload stored as a PE resource. Further inquiry reveals that SYK spreads multiple remote access Trojans and stealers, including WarzoneRAT, AsyncRAT, Quasar RAT, NanoCore RAT, RedLine Stealer, and more. 

SYK Crypter Analysis

According to Morphisec experts, SYK crypter is an innovative threat leveraging a broad range of evasive techniques to outsmart cyber defenders and bypass signature and behavior-based security controls. Specifically, SYK is able to detect and overcome the AV solutions, check for debugging environments, gain persistence through startup folder, and execute the payload using the process hollowing technique. 

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