Keylogger Injections on Microsoft Exchange Servers Threaten Global Government and Corporate Cybersecurity

Unidentified threat actors have targeted over 65 Microsoft Exchange servers across 26 countries by injecting malicious JavaScript keylogger codes into Outlook login pages. These attacks compromise credentials from government agencies, banks, IT firms, and educational institutions. This activity poses a significant global cybersecurity threat.

First detected in May 2024, this campaign traces back to compromises dating as far as 2021. This underscores the persistent and evolving nature of these intrusions.

Exploiting ProxyShell and ProxyLogon Vulnerabilities for Credential Theft

The attackers leverage multiple known Microsoft Exchange vulnerabilities, including ProxyShell (CVE-2021-34473, CVE-2021-34523, CVE-2021-31207) and ProxyLogon (CVE-2021-26855, CVE-2021-26857, CVE-2021-26858, CVE-2021-27065). These flaws allow remote code execution and bypass of security features.

By exploiting these vulnerabilities, malicious JavaScript is embedded into authentication pages. This enables attackers to harvest user credentials stealthily without raising alarms.

Did you know?
Despite patches being available since 2021, tens of thousands of Microsoft Exchange servers remain vulnerable to ProxyShell and ProxyLogon exploits. Many organizations remain exposed to credential theft and remote code execution attacks.

Dual Keylogger Variants Enhance Stealth and Persistence

Two distinct JavaScript keylogger variants have been identified. One saves stolen credentials to a local file accessible via the internet, minimizing outbound traffic and reducing detection risk.

The other variant transmits data immediately to external servers using covert channels such as Telegram bots and DNS tunnels. This dual methodology allows attackers to maintain persistent access while evading traditional security monitoring.

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Geographic and Sectoral Distribution of Victims

Victims span a broad geographic range, including Vietnam, Russia, Taiwan, China, Pakistan, Lebanon, Australia, Zambia, the Netherlands, and Turkey. Government organizations constitute the largest group affected.

The IT, industrial, and logistics sectors follow them. The widespread impact highlights the strategic targeting of critical infrastructure and sensitive sectors worldwide.

Challenges in Detection and Mitigation

The embedded keylogger code operates within legitimate authentication pages, making detection difficult. The absence of outbound traffic in some variants further complicates monitoring efforts.

Security experts emphasize the urgent need for organizations to patch known vulnerabilities promptly. Deploying advanced threat detection tools and conducting continuous monitoring of authentication endpoints are critical to mitigating risks.