CVE-2023-25690 is a critical vulnerability affecting Apache HTTP Server versions 2.4.0 through 2.4.55. This vulnerability allows HTTP Request Smuggling attacks due to certain mod_proxy configurations that can be exploited when mod_proxy is enabled alongside specific RewriteRule or ProxyPassMatch directives. The implications of this vulnerability are severe, as it could lead to bypassing access controls, unintended URL proxying, and cache poisoning.
The CVSS score for this vulnerability is 9.8, indicating a critical severity level. This score is primarily attributed to the high potential for confidentiality, integrity, and availability impacts, highlighting the urgency for organizations to address this vulnerability promptly. The exploitability score of 3.9 further emphasizes the ease with which attackers could potentially exploit this flaw.
Organizations using affected versions are strongly advised to update to at least version 2.4.56 to mitigate the risks associated with this vulnerability. The presence of public proof-of-concept (PoC) exploits enhances the urgency of applying the recommended patches.
Given the critical nature of this vulnerability, organizations should prioritize patching immediately. The potential for exploitation combined with the straightforward attack vector necessitates swift action from security teams.
Vulnerability Details
The official description of CVE-2023-25690 states that some mod_proxy configurations on Apache HTTP Server versions 2.4.0 through 2.4.55 allow a HTTP Request Smuggling attack. Configurations are affected when mod_proxy is enabled along with some form of RewriteRule or ProxyPassMatch in which a non-specific pattern matches some portion of the user-supplied request-target (URL) data and is then re-inserted into the proxied request-target using variable substitution.
For example, a configuration might look like the following: RewriteEngine on RewriteRule "^/here/(.*)" "http://example.com:8080/elsewhere?$1"; [P] ProxyPassReverse /here/ http://example.com:8080/ Request splitting or smuggling could result in a bypass of access controls in the proxy server, proxying unintended URLs to existing origin servers, and cache poisoning.
The affected product is the Apache HTTP Server, with a CVSS score of 9.8, classified as critical. The vulnerability was published on March 7, 2023, and falls under CWE-444.
Technical Analysis
The root cause of this vulnerability lies in the misconfiguration of the mod_proxy module within Apache HTTP Server. When mod_proxy is enabled, it can accept user-supplied request-target data, which is then processed according to the defined rules. If these rules are not strictly defined, they can be manipulated to execute unintended actions.
The attack vector is network-based, requiring no user interaction, and the complexity of the attack is low. Attackers do not need any privileges, making it accessible for exploitation. The impacts of this vulnerability are significant, as it can lead to high confidentiality, integrity, and availability impacts.
Risk & Impact Analysis
Risk to organizations includes the potential for unauthorized access, data leakage, and service disruption. The ability for attackers to exploit this vulnerability and manipulate proxied requests can result in significant operational and reputational damage.
The blast radius of this vulnerability is extensive, affecting all configurations of Apache HTTP Server versions 2.4.0 to 2.4.55 that utilize mod_proxy. Organizations must consider the implications of this vulnerability in their risk assessments and prioritize remediation efforts accordingly.
Given the critical CVSS score, organizations should prioritize patching immediately. The exploitation status indicates that public exploits are available, further emphasizing the need for timely action.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | Yes |
Public PoC | Yes |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
This vulnerability affects Apache HTTP Server versions 2.4.0 through 2.4.55. Organizations are advised to update to at least version 2.4.56 to mitigate the risks associated with this vulnerability.
Mitigation & Remediation
Organizations should apply patches to their Apache HTTP Server installations as soon as possible. The recommended version to upgrade to is 2.4.56 or later. If immediate patching is not feasible, organizations should implement workarounds by disabling mod_proxy or ensuring strict patterns in RewriteRule and ProxyPassMatch directives.
Additionally, configuration hardening should be performed to validate that only intended URLs are proxied, and network controls should be established to monitor traffic to prevent unauthorized access.
Organizations should also consider performing continuous security testing to identify similar vulnerabilities in their environments. More information on this process can be found in our detailed guide on continuous penetration testing.
Detection Guidance
Organizations should monitor logs for unusual request patterns that may indicate an attempt to exploit this vulnerability. Key indicators include unexpected 404 responses or requests that utilize unusual URL structures. Additionally, behavioral anomalies in web application performance should be tracked, along with network signatures that may signify exploitation attempts.
AppSecure Threat Intelligence Insight
The long-term significance of CVE-2023-25690 highlights the critical need for organizations to adopt secure configuration practices when deploying web servers. As vulnerabilities like this continue to surface, they represent a pattern where misconfigurations can lead to severe security issues.
Security teams should take this opportunity to reevaluate their configurations and ensure they follow best practices. Continuous monitoring and security assessments are vital to staying ahead of potential threats.
For further insights, consider exploring our resources on penetration testing methodology and vulnerability management programs to enhance your security posture.
Additionally, understanding the implications of this vulnerability will aid in developing API security testing strategies to minimize risks.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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