Pierluigi Paganini July 11, 2024

Multiple threat actors exploit a recently disclosed security PHP flaw CVE-2024-4577 to deliver multiple malware families.

The Akamai Security Intelligence Response Team (SIRT) warns that multiple threat actors are exploiting the PHP vulnerability CVE-2024-4577 to deliver multiple malware families, including Gh0st RAT, RedTail cryptominers, and XMRig.

“Threat actors continued the speedy-time-from-disclosure-to-exploitation trend and were quick to leverage this new vulnerability — we observed exploit attempts targeting this PHP flaw on our honeypot network within 24 hours of its disclosure.” reported Akamai.

The flaw CVE-2024-4577 (CVSS score: 9.8) is a PHP-CGI OS Command Injection Vulnerability. The issue resides in the Best-Fit feature of encoding conversion within the Windows operating system. An attacker can exploit the flaw to bypass protections for a previous vulnerability, CVE-2012-1823, using specific character sequences. Consequently, arbitrary code can be executed on remote PHP servers through an argument injection attack, allowing attackers to take control of vulnerable servers.

Since the disclosure of the vulnerability and public availability of a PoC exploit code, multiple actors are attempting to exploit it, reported Shadowserver and GreyNoise researchers.

In June, the U.S. Cybersecurity and Infrastructure Security Agency (CISA) added the the vulnerability to its Known Exploited Vulnerabilities (KEV) catalog.

Greynoise researchers also reported malicious attempts of exploitation of the CVE-2024-4577.

“As of this writing, it has been verified that when the Windows is running in the following locales, an unauthorized attacker can directly execute arbitrary code on the remote server:

• Traditional Chinese (Code Page 950)
• Simplified Chinese (Code Page 936)
• Japanese (Code Page 932)

For Windows running in other locales such as English, Korean, and Western European, due to the wide range of PHP usage scenarios, it is currently not possible to completely enumerate and eliminate all potential exploitation scenarios.” continues the advisory. “Therefore, it is recommended that users conduct a comprehensive asset assessment, verify their usage scenarios, and update PHP to the latest version to ensure security.

Akamai researchers also observed threat actors behind the DDoS botnet Muhstik exploiting this vulnerability.

The botnet shell script downloads an ELF file named “pty3” from a different IP address, likely a sample of Muhstik malware. The malware was designed to targets Internet of Things (IoT) devices and Linux servers for cryptomining and DDoS purposes. The bot also connects to the command and control domain p.findmeatthe[.]top, which was observed in Muhstik botnet activities, and communicates via Internet Relay Chat.

The researchers also observed a campaign abusing the exploit to deliver the XMR Rig. The attackers injected a command that relies on a PowerShell script to download and execute a script to spin up XMRig from a remote mining pool. The script also cleans up the temporary files for obfuscation.

“Between the use of various automation tools and a lack of corporate oversight, attackers are set up to succeed. The continuously shrinking time that defenders have to protect themselves after a new vulnerability disclosure is yet another critical security risk.” concludes the report. “This is especially true for this PHP vulnerability because of its high exploitability and quick adoption by threat actors.”

Pierluigi Paganini

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(SecurityAffairs – hacking, PHP flaw CVE-2024-4577)