The Unrelenting Evolution of GuLoader and Malware Sophistication

Security researchers are continuously waging war against sophisticated malware operators, with GuLoader posing as one principal adversary. GuLoader is a shellcode-based malware downloader, operational since 2019, known for distributing malicious payloads like information stealers. Ensuring evasion of detection, GuLoader uses advanced obfuscation techniques making its analysis tedious and resource-intensive. The codename may change but the malware persists; GuLoader has recently been put up on sale under a new name on the same platform as Remcos[source].

The latest enhancement of GuLoader involves deploying Vectored Exception Handling (VEH) to disrupt the code execution flow. VEH generates countless exceptions, making it troublesome for researchers to scrutinize thus enhancing its stealth capabilities[source].

GuLoader isn’t the sole minion to constantly update its anti-detection techniques. DarkGate, Agent Tesla, and AsyncRAT are other notable examples of malware-as-a-service offerings that regularly adapt to elude antivirus measures[source][source][source].

Threat actors behind GuLoader have a pronounced inclination towards dispatching malware through phishing campaigns, causing victims to download and install it from email attachments or links containing VBScript files[source]. Similarly, DarkGate utilizes deceptive email campaigns to disseminate the initial infection vector[source]. Agent Tesla and AsyncRAT also exhibit novel email-based infection chains to bypass antivirus measures[source][source].

Interestingly, dark web marketplaces supply readily available threats like the RedLine stealer malware. Threat actors use the updated ScrubCrypt (aka BatCloak) obfuscation engine to deliver this particular malware variant[source].

These developments underline the persistent evolution and sophistication of malware threats. As such, it is crucial for cybersecurity solutions and researchers to adopt agile and robust tactics to mitigate these fast-evolving threats. The incessant game of cat and mouse between malware creators and security researchers indeed continues.