PHP command injection flaw exploited to deliver ransomware (CVE-2024-4577)

PHP, when the interpreter is exposed through the CGI (php-cgi) interface, mishandles query strings (CWE-20 improper input validation), allowing attackers to pass command-line switches such as -d and -s directly to the interpreter. A remote, unauthenticated attacker triggers the flaw by sending a crafted query string beginning with a dash (including URL-encoded forms) to any URL handled by php-cgi. Successful exploitation allows arbitrary code execution under the web server's privileges, as well as disclosure of script source code or phpinfo output, with no authentication required. Only deployments that invoke PHP via CGI/FastCGI (common in legacy shared hosting and bundled software stacks) are affected; PHP running as an Apache module or via PHP-FPM is not exposed. The flaw was added to CISA's Known Exploited Vulnerabilities catalog on 2022-03-25 with EPSS at 100%, indicating active in-the-wild exploitation; any ransomware association is not yet confirmed.

Do: Upgrade PHP to at least 5.3.13/5.4.3 or, preferably, a currently supported PHP branch, and stop exposing the php-cgi binary directly by moving to mod_php or PHP-FPM. As an interim mitigation, block or rewrite requests whose query string begins with a dash (e.g., -d, -s, or URL-encoded dash characters) and review web server logs for such patterns to detect prior exploitation.

CVE-2024-4577 is an OS command injection flaw (CWE-78) in Windows-based PHP when it runs in CGI mode, allowing arbitrary code execution on the server. It is triggered when attacker-supplied characters in HTTP requests are mishandled by Windows' character-encoding conversion as the OS invokes php-cgi, letting attackers inject command-line arguments to the PHP interpreter; this bypasses the decade-old fix for CVE-2012-1823. A successful attacker gains the ability to run arbitrary commands and code in the context of the web server. Affected systems are PHP running on Windows through the CGI interface; deployments that do not use PHP-CGI on Windows are not described as affected in the source data. Exploitation is active: the flaw was added to CISA KEV on 2024-06-12 with known ransomware use, and EPSS assigns roughly 100% probability of exploitation within 30 days.

Do: Per the CISA KEV required action, apply mitigations per vendor instructions or discontinue use: upgrade Windows PHP-CGI deployments to a PHP release that fixes CVE-2024-4577 per PHP Group advisories, or stop using CGI mode on Windows (e.g., switch to FastCGI) and apply any vendor-recommended workarounds. Given known ransomware abuse, review web server access logs for exploitation attempts (notably %AD-encoded soft hyphens and injected -d/-s arguments in php-cgi query strings) and prioritize patching internet-facing Windows hosts.