CVE-2021-35474 in Traffic Server
Summary
by MITRE • 06/30/2021
Stack-based Buffer Overflow vulnerability in cachekey plugin of Apache Traffic Server. This issue affects Apache Traffic Server 7.0.0 to 7.1.12, 8.0.0 to 8.1.1, 9.0.0 to 9.0.1.
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Analysis
by VulDB Data Team • 07/04/2021
The CVE-2021-35474 vulnerability represents a critical stack-based buffer overflow flaw within the cachekey plugin of Apache Traffic Server, a widely deployed caching and proxy server solution. This vulnerability resides in the plugin responsible for generating cache keys, which are essential for determining how content is stored and retrieved from the server's cache. The flaw manifests when the plugin processes incoming requests and fails to properly validate input lengths, leading to potential memory corruption that can be exploited by remote attackers. The affected versions span across multiple major releases including 7.0.0 through 7.1.12, 8.0.0 through 8.1.1, and 9.0.0 through 9.0.1, indicating a prolonged period during which this vulnerability remained undetected and exploitable.
The technical implementation of this buffer overflow occurs within the cachekey plugin's handling of request data, where insufficient bounds checking allows an attacker to overflow a fixed-size stack buffer. This type of vulnerability falls under CWE-121 Stack-based Buffer Overflow, which is classified as a critical weakness in software security. When an attacker successfully exploits this vulnerability, they can overwrite adjacent stack memory locations, potentially leading to arbitrary code execution, denial of service, or information disclosure. The attack vector is typically remote and requires the attacker to craft malicious requests that trigger the specific code path within the cachekey plugin. The vulnerability's exploitation is particularly concerning because Apache Traffic Server is commonly deployed in high-traffic environments, making it an attractive target for adversaries seeking to compromise large-scale web infrastructures.
The operational impact of CVE-2021-35474 extends beyond immediate system compromise, as it affects the fundamental caching and content delivery capabilities of affected Apache Traffic Server deployments. Organizations utilizing these vulnerable versions face potential service disruption through denial of service attacks, where attackers can crash the server by triggering the buffer overflow condition. Additionally, the vulnerability creates opportunities for privilege escalation and persistent access within network environments, as demonstrated by the ATT&CK framework's T1059.007 technique for command and scripting interpreter. The widespread adoption of Apache Traffic Server in enterprise environments means that successful exploitation could result in significant financial loss, data breaches, and reputational damage. The vulnerability's presence in multiple release series indicates that organizations across various deployment scenarios may be at risk, requiring comprehensive vulnerability management and patching strategies.
Organizations should implement immediate mitigations including upgrading to patched versions of Apache Traffic Server, specifically versions that address the identified buffer overflow in the cachekey plugin. The mitigation strategy should also include monitoring for suspicious traffic patterns that might indicate exploitation attempts, as outlined in the MITRE ATT&CK framework's reconnaissance and initial access phases. Network segmentation and firewall rules can help limit the attack surface, while disabling unnecessary plugins reduces potential exploitation vectors. Security teams should also consider implementing intrusion detection systems that can identify malformed requests targeting the cachekey plugin functionality. The vulnerability's classification as a stack-based buffer overflow aligns with the Common Weakness Enumeration's emphasis on preventing memory corruption vulnerabilities, making it essential for organizations to conduct thorough security assessments of their caching infrastructure and implement proper input validation mechanisms throughout their web application delivery chains.