From a Regular Infostealer to its Obfuscated Version – SANS Internet Storm Center

Summary:
This article discusses the obfuscation techniques used in malicious scripts, specifically focusing on the Trap-Stealer info stealer. It highlights how attackers employ various methods to hide their code, making it challenging for security analysts to detect and analyze. The article provides a practical example of obfuscation through unnecessary classes, variables, and encryption techniques.
#ObfuscationTechniques #MaliciousScripts #InfoStealer


Keypoints:

  • Malicious scripts like Trap-Stealer are available on platforms like Github.
  • Obfuscation techniques are used to complicate the analysis of malicious code.
  • The example provided shows a fake JPEG file used to hide malicious code.
  • Unnecessary classes and variables are included to confuse security analysts.
  • Base64 encoding is used to obscure the payload of the malicious script.
  • Multiple encryption keys are tested to decrypt the hidden payload.
  • Tools for obfuscation are often included in the malware repository.

MITRE Techniques

  • Obfuscated Files or Information (T1027): Uses obfuscation techniques to hide the true nature of the code.
  • Data Encrypted (T1022): Encrypts data to prevent detection and analysis.
  • Command and Control (T1071): Utilizes various methods to maintain communication with compromised systems.

IoC:

  • [file name] apxpvddh.jpeg
  • [url] github[.]com/TheCuteOwl/Trap-Stealer
  • [url] virustotal[.]com/gui/file/85a0342027420025c477f3f6ab68376aa1608a447d1fb24920ac36b7cf7fd59d/detection
  • [url] github[.]com/TheCuteOwl/Trap-Stealer/blob/main/obfuscator.py

Mitigation:

  • Implement strict security measures to monitor and block malicious scripts from running.
  • Utilize advanced threat detection tools that can analyze obfuscated code.
  • Educate security analysts on common obfuscation techniques to improve detection capabilities.
  • Regularly update security software to recognize new threats and obfuscation methods.

  • Full Research: https://isc.sans.edu/diary/From+a+Regular+Infostealer+to+its+Obfuscated+Version/31484/