Analysis Summary

Cybersecurity researchers have discovered a new attack exploiting a vulnerability in Google Chrome version 133.0.6943.126 using DLL side-loading techniques.

According to the Researcher, this method allows attackers to execute malicious code by replacing the legitimate chrome_elf.dll file with a malicious one, leveraging Chrome’s trusted subprocesses to evade detection. The attack is particularly concerning as it exploits Windows' DLL search order, enabling the malicious DLL to load before the legitimate one, compromising system security.

The exploit takes advantage of DLL proxying, where the malicious DLL intercepts function calls and forwards them to the original DLL, ensuring Chrome continues to function normally while executing hidden malicious code. Security analysts highlight that this attack creates a persistent backdoor, enabling long-term access even after Chrome is closed. Detection rates are extremely low, with security tools flagging the malicious DLL in only 2 out of 70 scans, as it employs anti-detection techniques. A notable aspect is that the malware is written in Nim, a rare language in cyber threats, making analysis more challenging for security researchers.

Despite Google’s recent security updates for Chrome 133, this specific DLL side-loading vulnerability remains unpatched, affecting Windows, macOS, and Linux versions. The attack highlights the ongoing evolution of threat tactics, as DLL side-loading has been used since at least 2010 but is now being applied to widely-used software like Chrome, increasing its impact. This attack emphasizes the growing sophistication of cyber threats, where attackers refine established techniques to bypass modern security defenses.

To mitigate the risk, users must update Chrome immediately, implement endpoint detection solutions, use application whitelisting to block unauthorized DLL loading, and monitor system behavior for anomalies after closing Chrome. Given the attack’s stealth and persistence, organizations should adopt proactive security measures to defend against such evolving threats, ensuring that their systems are safeguarded against DLL side-loading exploitation.

Impact

• Code Execution
• Security BypassUnauthorized Access

Indicators of Compromise

MD5

• 9289cc6615c40e94fd2fc1ad0042673a

SHA-256

• 9b5c56d95298d8863fe346ea99605aa4729f27ec5dd195fe7d5eda32fbf80ca4

SHA-1

• 7c0e2492f2e16c93175245fb00556abad8fceb06

Remediation

• Block all threat indicators at your respective controls.
• Search for indicators of compromise (IOCs) in your environment utilizing your respective security controls.
• Ensure your browser is updated to the latest version to patch potential vulnerabilities.
• Use advanced security tools capable of detecting DLL side-loading techniques.
• Restrict unauthorized DLL execution by allowing only trusted applications and libraries.
• Track suspicious activity, especially unexpected processes running after Chrome is closed.
• Periodically review system integrity and check for unauthorized DLL modifications.
• Use behavioral analysis and heuristic-based detection methods to identify stealthy malware.
• Limit write permissions to prevent unauthorized DLL replacements.
• Raise awareness about phishing and malware tactics that could facilitate DLL side-loading attacks.