CVE-2017-6056 in Instantis EnterpriseTrack
Summary
by MITRE
It was discovered that a programming error in the processing of HTTPS requests in the Apache Tomcat servlet and JSP engine may result in denial of service via an infinite loop. The denial of service is easily achievable as a consequence of backporting a CVE-2016-6816 fix but not backporting the fix for Tomcat bug 57544. Distributions affected by this backporting issue include Debian (before 7.0.56-3+deb8u8 and 8.0.14-1+deb8u7 in jessie) and Ubuntu.
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Analysis
by VulDB Data Team • 08/25/2024
The vulnerability identified as CVE-2017-6056 represents a critical denial of service flaw within the Apache Tomcat web server implementation that specifically affects the processing of HTTPS requests through the servlet and JSP engine components. This issue emerged from a problematic backporting strategy that inadvertently introduced a programming error during the security update process. The flaw manifests as an infinite loop during request processing, which can be easily exploited to disrupt service availability for legitimate users. The vulnerability is particularly concerning because it demonstrates how security updates can introduce new weaknesses when not carefully coordinated across multiple versions and patches.
The technical root cause of this vulnerability stems from a programming error in the HTTPS request handling mechanism within Tomcat's servlet container. When processing certain HTTPS requests, the system enters an infinite loop due to improper state management or control flow logic that was introduced during the backporting of CVE-2016-6816 fix without properly implementing the corresponding fix for Tomcat bug 57544. This creates a condition where the server continuously processes the same request without making forward progress, consuming system resources and ultimately leading to service disruption. The flaw specifically impacts the HTTPS protocol handling within the servlet and JSP engine, making it particularly dangerous for web applications that rely heavily on secure communication channels.
The operational impact of CVE-2017-6056 is severe and directly affects system availability and service reliability for affected organizations. Attackers can easily trigger this denial of service condition through carefully crafted HTTPS requests, requiring minimal technical expertise to exploit. The vulnerability affects Debian and Ubuntu distributions that have not properly updated their Tomcat implementations, creating a widespread risk across various server environments. Organizations running affected versions of Tomcat may experience complete service outages, with the infinite loop consuming CPU cycles and memory resources until the system becomes unresponsive. This makes the vulnerability particularly dangerous in production environments where service availability is critical for business operations.
The vulnerability aligns with CWE-835, which addresses the issue of infinite loops in software systems, and demonstrates how improper patch management can create new security weaknesses rather than resolving existing ones. From an ATT&CK framework perspective, this vulnerability maps to the T1499.004 technique involving network denial of service attacks through resource exhaustion. Organizations should implement comprehensive patch management procedures that ensure complete coordination between security fixes and prevent partial backporting that creates inconsistencies. The recommended mitigations include updating to patched versions of Tomcat that properly address both CVE-2016-6816 and Tomcat bug 57544, implementing rate limiting and request validation mechanisms, and monitoring for unusual resource consumption patterns that may indicate exploitation attempts. Additionally, security teams should establish rigorous testing procedures for security updates to verify that patches do not introduce new vulnerabilities during the update process.