Threat Actors Exploit PHP-CGI RCE Vulnerability to Attack Windows Machines

A recent cybersecurity threat has emerged where unknown attackers are exploiting a critical remote code execution (RCE) vulnerability in PHP-CGI on Windows systems.

This vulnerability, identified as CVE-2024-4577, allows attackers to execute arbitrary PHP code on servers using Apache with a vulnerable PHP-CGI setup.

The attackers are primarily targeting organizations in Japan across various sectors, including technology, telecommunications, entertainment, education, and e-commerce.

Exploitation and Post-Exploitation Activities

The attackers gain initial access by leveraging a publicly available Python exploit script that checks for the CVE-2024-4577 vulnerability.

Once exploited, they execute a PowerShell command embedded in PHP code, which downloads and runs a PowerShell injector script from a command and control (C2) server.

According to Cisco Talos Report, This script injects and executes Cobalt Strike reverse HTTP shellcode, enabling remote access to the victim machine.

The attackers then use plugins from the Cobalt Strike “TaoWu” kit for post-exploitation activities, including reconnaissance, privilege escalation, and persistence.

They employ tools like JuicyPotato, RottenPotato, and SweetPotato for privilege escalation, and modify registry keys and create scheduled tasks to maintain persistence.

The attackers also engage in network reconnaissance using tools like “fscan.exe” and “Seatbelt.exe” to map potential targets for lateral movement.

They attempt to abuse Group Policy Objects (GPOs) to execute malicious scripts across the network.

Additionally, they use Mimikatz to dump and exfiltrate passwords and NTLM hashes from memory.

To evade detection, they clear Windows event logs using “wevtutil.exe.”

Misuse of Legitimate Tools and Frameworks

The attackers have been observed misusing legitimate tools and frameworks hosted on an Alibaba cloud container registry.

They use a pre-configured installer script to deploy a suite of adversarial tools, including Vulfocus, Asset Reconnaissance Lighthouse (ARL), Viper C2, Starkiller, BeEF, and Blue-Lotus.

These tools are typically used for offensive security testing but are being repurposed for malicious activities.

The attackers’ tactics show similarities with those used by known hacker groups, though attribution remains uncertain.

The ongoing exploitation of public-facing applications for initial access highlights the importance of patching vulnerabilities and implementing robust security measures.

Organizations should prioritize securing their PHP-CGI implementations and monitoring for suspicious activity to mitigate these threats.

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