Raspberry Robin Malware Shifts Tactics, Spreads via Windows Script Files

Raspberry Robin Malware Shifts Tactics, Spreads via Windows Script Files to Evade Detection

Raspberry Robin Malware Shifts Tactics, Spreads via Windows Script Files

The operators behind the Raspberry Robin malware distribution platform have evolved their tactics, now leveraging Windows Script Files (.wsf) to infect systems in a way that evades detection and makes analysis more difficult.

Table of Contents

Background on Raspberry Robin Malware

A modular malware ecosystem first revealed by Red Canary in 2022, Raspberry Robin is often used as a precursor to ransomware attacks. Among the key characteristics are:

1. USB drives, malicious ads, and now Windows Script Files were the first sources of infection
2. Execution/persistence using Windows Installer, LNK files, DLLs, and scripts
3. A precursor to malware such as Cobalt Strike, SocGholish, IcedID, and ransomware
4. To download additional payloads, command and control communication is required

Transition to Stealthy .WSF File Infections

The operators behind Raspberry Robin have switched to using obfuscated Windows Script Files in a recent campaign discovered by HP Threat Research:

1. JScript and VBScript can be mixed in.WSF files for flexible code execution

2. Scripts are made evasive by obfuscation techniques:

   Runtime decoding of encoded functions/variables
3. Code that obfuscates control flow and self-destructs
4. To avoid detection, check for sandboxes and virtual environments
5. Bypasses antivirus when downloading payloads using exceptions

Threat actors benefit greatly from these .wsf files:

• Many security controls designed for executable malware are bypassed
• Analysts struggle to reverse engineer and understand
• Its native execution through Windows Script Host makes Raspberry Robin a common precursor to ransomware attacks. Raspberry Robin is a modular malware ecosystem first revealed by Red Canary in 2022. Among the key characteristics are:
• The first sources of infection were USB drives, malicious ads, and now Windows Script Files
• Scripts, LNK files, DLLs, and Windows Installer for execution/persistence
• Cobalt Strike, SocGholish, IcedID, and ransomware are precursors to this type of malware
• Command and control communication is required to download additional payloads

Raspberry Robin Malware Shifts Tactics, Spreads via Windows Script Files

In-Depth Technical Analysis of the.WSF Attack Flow

Using these stealthy .wsf scripts, infection proceeds as follows:

1. A script file is executed on the target system, evading antivirus protection by using exceptions
2. To avoid sandboxes and analysis, environment checks are run
3. Extraction and decryption of encoded C2 server URLs
4. Downloaded malicious Raspberry Robin DLL from C2 and saved it to disk
5. A script host executes a DLL, infecting the machine and enabling further payloads to execute

Consequently, malware executables are increasingly being replaced by scripts that are more difficult to analyze. Compared to USB-based spreading, Windows Script Host eliminates several hurdles for attackers.

Defending Against This Emerging Script Malware Threat

Because Windows Script Files can access system resources and support multiple languages, threat actors are increasingly interested in them. Several key defences exist, including:

1. Detecting obfuscated scripts by updating antivirus and endpoints
2. System monitoring for suspicious script execution and traffic
3. Identifying malware by analyzing scripts in sandboxes
4. Hardening systems to mitigate vulnerabilities according to best practices
5. Script-based attacks: user education

The best way to defend against this growing trend towards stealthy script-based malware is to stay vigilant against new developments with Raspberry Robin and implement layered mitigations.

Outlook on Raspberry Robin Evolution

Due to its continuous shifting, Raspberry Robin is likely to take on new forms in future campaigns. Detecting this malware as it evolves requires organizations to proactively monitor for new variants, analyze suspicious activity thoroughly, and implement robust security controls.