CVE-2021-44790 is a critical vulnerability affecting the Apache HTTP Server that enables a buffer overflow through a carefully crafted request body within the mod_lua multipart parser. Specifically, this vulnerability arises when the r:parsebody() function is called from Lua scripts. With a CVSS score of 9.8, it is classified as critical due to its high potential impact on confidentiality, integrity, and availability.
The Apache HTTP Server team has stated that although they are not aware of any public exploit, there remains a possibility that an exploit could be developed. This vulnerability particularly affects Apache HTTP Server versions 2.4.51 and earlier, making it crucial for organizations using these versions to apply mitigation strategies immediately.
Risk to organizations includes potential unauthorized access and denial of service, stemming from the ability of an attacker to exploit this vulnerability remotely without needing any authentication or user interaction. Given the critical nature of this vulnerability, organizations should prioritize patching immediately.
The urgency for defenders cannot be overstated; immediate action is required to safeguard systems against possible exploitation. Patch updates are available, and organizations should ensure they are applied promptly to mitigate risks.
Vulnerability Details
The official CVE description states: 'A carefully crafted request body can cause a buffer overflow in the mod_lua multipart parser (r:parsebody() called from Lua scripts). The Apache HTTPD team is not aware of an exploit for the vulnerability though it might be possible to craft one. This issue affects Apache HTTP Server 2.4.51 and earlier.'
This vulnerability is classified under CWE-787, which indicates a buffer overflow. The CVSS score of 9.8 categorizes it as critical, indicating a severe threat to systems, especially those that handle sensitive data or are exposed to the internet.
Affected products include Apache HTTP Server, Fedora, Debian Linux, and others that utilize the mod_lua parser. The vulnerability was published on December 20, 2021, and remains a significant threat due to its potential for exploitation.
Technical Analysis
The root cause of CVE-2021-44790 stems from inadequate input validation in the mod_lua multipart parser, which allows crafted requests to overflow buffers. The attack vector is network-based, making it easily exploitable by remote attackers without the need for authentication.
The attack complexity is low, requiring no special conditions or user interaction. Consequently, any attacker who can send a crafted request can exploit this vulnerability. The potential impacts are severe, with confidentiality, integrity, and availability all rated as high, indicating that successful exploitation could lead to significant system compromise.
Risk & Impact Analysis
Organizations utilizing affected versions of Apache HTTP Server face substantial risks. The potential for unauthorized access and system failure poses a serious threat, particularly for those managing sensitive information or critical applications. The blast radius of this vulnerability extends to any system exposed to the network where the Apache HTTP Server operates, elevating the urgency for remediation.
Given the CVSS score of 9.8, organizations should recognize the critical nature of this vulnerability. The presence of this vulnerability in publicly accessible systems can lead to exploitation, emphasizing the need for immediate patching. In light of the exploitation potential, organizations must act swiftly to secure their environments.
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 2.4.51 and earlier. If version information is missing, it can be stated that all versions prior to the vendor patch are affected.
Mitigation & Remediation
Organizations should immediately apply patches to affected systems. The official fix is available for Apache HTTP Server, and upgrading to version 2.4.52 or later will mitigate this vulnerability. For those unable to patch, consider alternative measures such as employing Web Application Firewalls (WAF) to filter malicious requests and implementing strict input validation to minimize risks.
For further guidance on securing your applications, organizations can refer to our resource on application security assessment and best practices.
Detection Guidance
Organizations should monitor logs for indicators of exploitation attempts, such as unusual request patterns or unexpected errors in the mod_lua functionality. Behavioral anomalies in server performance or response times may also indicate potential exploitation. Implementing network signatures to detect malformed requests can further enhance detection capabilities.
AppSecure Threat Intelligence Insight
The long-term significance of CVE-2021-44790 is profound, as it highlights vulnerabilities that may arise from complex systems integrating multiple technologies. This incident serves as a reminder to security teams to regularly review and update their security posture against evolving threats.
Security teams should focus on understanding the patterns of vulnerabilities appearing in widely used technologies like Apache. Continuous monitoring and proactive vulnerability management strategies are essential to safeguard against such critical vulnerabilities.
For more insights into managing vulnerabilities, organizations can explore our guide on vulnerability management programs and enhancing their security frameworks.
Finally, organizations are encouraged to engage in penetration testing to validate their defenses and readiness against similar vulnerabilities.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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