CVE-2024-40898 in HTTP Server
Summary
by MITRE • 07/18/2024
SSRF in Apache HTTP Server on Windows with mod_rewrite in server/vhost context, allows to potentially leak NTML hashes to a malicious server via SSRF and malicious requests.
Users are recommended to upgrade to version 2.4.62 which fixes this issue.
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Analysis
by VulDB Data Team • 11/07/2024
The vulnerability identified as CVE-2024-40898 represents a critical server-side request forgery flaw within the Apache HTTP Server implementation on Windows platforms. This issue specifically affects systems utilizing mod_rewrite functionality within server or virtual host contexts, creating a pathway for malicious actors to exploit the server's request handling mechanisms. The vulnerability stems from insufficient validation of URLs within rewrite rules, allowing crafted requests to bypass normal security boundaries and potentially expose sensitive authentication information.
The technical exploitation of this vulnerability occurs through carefully constructed requests that leverage the mod_rewrite module's URL processing capabilities. When Apache processes these malicious requests, it fails to properly sanitize or validate the destination URLs, enabling attackers to redirect requests to internal services or external malicious servers. The flaw specifically manifests when the server processes rewrite directives that reference URLs without adequate security controls, creating an opportunity for NTLM hash leakage. This occurs because the server's authentication handling does not properly isolate or validate the targets of redirected requests, particularly when dealing with Windows authentication mechanisms.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with potential access to NTLM authentication hashes that can be used for further credential compromise. These hashes can be leveraged in various attack scenarios including pass-the-hash attacks, where adversaries use the captured credentials to authenticate to other systems within the network. The vulnerability affects organizations running Apache HTTP Server on Windows platforms where mod_rewrite is configured in server or virtual host contexts, potentially exposing entire network infrastructures to unauthorized access. The attack vector requires minimal privileges and can be executed through standard HTTP request manipulation, making it particularly dangerous for environments with limited security monitoring.
Organizations should immediately implement the recommended mitigation by upgrading to Apache HTTP Server version 2.4.62, which contains the necessary patches to address this vulnerability. Additional defensive measures include implementing strict URL validation for all mod_rewrite directives, configuring proper network segmentation to limit internal service exposure, and deploying enhanced monitoring for unusual outbound requests. The vulnerability aligns with CWE-918, which describes server-side request forgery vulnerabilities, and maps to ATT&CK technique T1190 for exploit public-facing application, while also relating to T1078 for valid accounts and T1566 for spearphishing. Security teams should conduct immediate assessments of their Apache configurations to identify and remediate any instances of mod_rewrite rules that might be vulnerable to this class of attack, particularly focusing on any rules that reference external URLs or internal services without proper validation controls.