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CVE-2024-4577 is a critical remote code execution vulnerability discovered in the PHP CGI module running on Windows operating systems.
The security flaw stems from how the Windows Win32 API handles command-line arguments and character encoding translations.
When Windows processes command-line parameters, it can apply a Best-Fit mapping behavior to substitute unsupported characters.
The PHP CGI binary incorrectly interprets these substituted character sequences as command-line options rather than harmless query parameters.
An unauthenticated remote attacker can exploit this behavior by submitting specially crafted HTTP requests containing specific byte sequences.
These malicious sequences typically include soft hyphens or encoded characters that translate into command switches like -s, -d, or -n.
Because the PHP binary processes these injected options during execution, it alters its runtime configuration or source display behavior.
Attackers leverage this parameter injection to pass malicious directives directly into the PHP runtime environment without authentication.
By chaining these flags with directives like `allow_url_include` or auto_prepend_file, attackers can supply arbitrary PHP payload code.
The web server executes this payload with the privileges of the user running the PHP CGI process, leading to full system compromise.
The vulnerability impacts multiple PHP branches running on Windows servers, particularly when scripts are accessed directly via CGI.
Traditional web application firewalls and basic input filters often fail to catch the encoded byte sequences at the operating system layer.
Because the translation happens during parameter parsing in the underlying Windows API, application-level sanitization routines are bypassed.
Emergency patches were released by the PHP development team to address this severe flaw by enforcing strict parameter validation checks.
Administrators running PHP on Windows platforms must update their binaries immediately or switch to secure execution architectures like FastCGI.
DailyCVE Form:
Platform: PHP CGI Windows
Version: Pre 8.1.29
Vulnerability: Remote Code Execution
Severity: Critical risk level
date: June sixth 2024
Prediction: Patched in June
What Undercode Say:
Showing bash commands and codes related to the blog
curl "http://target/index.php?%ADd+allow_url_include%3d1+%ADd+auto_prepend_file%3dphp://input" -d "<?php system('id'); ?>"
Exploit: (Educational Purposes!)
The exploit targets the parameter parsing mechanism of PHP running in CGI mode on Windows systems. By injecting URL-encoded soft hyphens (%AD), the attacker tricks the Win32 API into mapping characters into valid PHP command-line flags. This allows the remote injection of runtime configuration options, enabling arbitrary code execution via HTTP request bodies.
Protection: from this CVE
Upgrade PHP installations immediately to secured versions 8.1.29, 8.2.20, 8.3.8, or later. If immediate patching is impossible, deploy web server rules to block requests containing suspicious query parameters and soft hyphen byte sequences, or migrate away from the vulnerable CGI mode entirely.
Impact:
Successful exploitation grants attackers unauthenticated remote code execution capabilities, allowing them to install persistent web shells, extract sensitive data, execute arbitrary system commands, and compromise the underlying host infrastructure.
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Sources:
Reported By: github.com
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