CVE-2013-4322 in Communications Policy Management
Summary
by MITRE
Apache Tomcat before 6.0.39, 7.x before 7.0.50, and 8.x before 8.0.0-RC10 processes chunked transfer coding without properly handling (1) a large total amount of chunked data or (2) whitespace characters in an HTTP header value within a trailer field, which allows remote attackers to cause a denial of service by streaming data. NOTE: this vulnerability exists because of an incomplete fix for CVE-2012-3544.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 09/27/2022
The vulnerability identified as CVE-2013-4322 represents a critical denial of service flaw affecting Apache Tomcat versions prior to specific patch releases. This issue stems from inadequate handling of chunked transfer encoding mechanisms within the HTTP protocol implementation. The flaw manifests when Tomcat processes HTTP requests containing chunked data streams, particularly when dealing with excessive data volumes or malformed trailer field values containing whitespace characters. The vulnerability was introduced due to an incomplete remediation of a previous vulnerability CVE-2012-3544, creating a persistent security gap that attackers can exploit to disrupt service availability.
The technical implementation of this vulnerability occurs at the HTTP protocol parsing layer within Tomcat's request processing pipeline. When chunked transfer encoding is employed, data is transmitted in discrete chunks rather than as a single contiguous block. The flaw arises during the parsing of trailer fields that appear after the final chunk, where Tomcat fails to properly validate or limit the amount of data processed. Specifically, the system does not adequately constrain the total volume of chunked data that can be accumulated during processing, nor does it correctly handle whitespace characters that may appear within HTTP header values in trailer fields. This improper handling leads to resource exhaustion or parsing errors that ultimately result in service disruption.
The operational impact of CVE-2013-4322 extends beyond simple service interruption to potentially compromise entire application availability. Attackers can leverage this vulnerability by establishing connections to the affected Tomcat servers and streaming chunked data in a manner designed to trigger the parsing flaw. The denial of service occurs through resource exhaustion, where the server consumes excessive memory or processing cycles attempting to handle the malformed data streams. This vulnerability is particularly dangerous in high-traffic environments where a single malicious connection can consume significant server resources, potentially affecting multiple concurrent users and applications hosted on the same server instance.
Mitigation strategies for CVE-2013-4322 require immediate deployment of patched Tomcat versions, specifically upgrading to 6.0.39, 7.0.50, or 8.0.0-RC10 and later releases. Organizations should implement network-level controls including firewall rules that limit chunked data transfer rates and connection timeouts to prevent exploitation. Additionally, monitoring systems should be configured to detect unusual patterns in HTTP request processing that may indicate exploitation attempts. The vulnerability aligns with CWE-400, which categorizes improper resource exhaustion, and maps to ATT&CK technique T1499.004 for network denial of service attacks. Security teams should also consider implementing intrusion detection systems that can identify malformed chunked transfer encoding patterns and establish baseline performance metrics to quickly detect service degradation indicative of exploitation.