CVE-2010-3476 in OTRS
Summary
by MITRE
Open Ticket Request System (OTRS) 2.3.x before 2.3.6 and 2.4.x before 2.4.8 does not properly handle the matching of Perl regular expressions against HTML e-mail messages, which allows remote attackers to cause a denial of service (CPU consumption) via a large message, a different vulnerability than CVE-2010-2080.
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Analysis
by VulDB Data Team • 09/25/2021
The Open Ticket Request System OTRS vulnerability CVE-2010-3476 represents a critical denial of service weakness that affects versions prior to 2.3.6 and 2.4.8. This vulnerability specifically targets the system's handling of Perl regular expressions when processing HTML email messages, creating a condition where maliciously crafted large email payloads can trigger excessive cpu consumption. The flaw exploits the regex matching algorithms used by OTRS to parse and process incoming email communications, making it particularly dangerous for organizations relying on ticketing systems for customer support and internal communications. Unlike other similar vulnerabilities such as CVE-2010-2080, this issue is specifically tied to the HTML message processing pipeline rather than general input validation.
The technical implementation of this vulnerability stems from the improper handling of regular expression matching operations within OTRS's email processing module. When the system encounters HTML formatted emails with complex nested structures or repetitive patterns, the Perl regex engine performs exponential backtracking during pattern matching operations. This occurs because the regular expressions used to extract specific information from HTML content contain constructs that cause the matching algorithm to explore an exponential number of possible matches. The vulnerability becomes particularly pronounced when dealing with large email messages containing extensive HTML formatting, nested tags, or repeated patterns that trigger the backtracking behavior in the underlying regex engine.
The operational impact of CVE-2010-3476 can be severe for organizations using affected OTRS versions, as remote attackers can easily consume significant system resources through carefully crafted email messages. This leads to complete denial of service conditions where legitimate users cannot access the ticketing system, and system administrators face performance degradation or complete system outages. The vulnerability can be exploited by sending a single large HTML email message that causes the system to spend excessive cpu cycles in regex processing, potentially leading to system crashes or requiring manual intervention to restore service. Organizations may experience cascading effects where the denial of service impacts customer support operations, business continuity, and overall productivity.
Mitigation strategies for CVE-2010-3476 should prioritize immediate patching of affected OTRS installations to versions 2.3.6 or 2.4.8 where the vulnerability has been addressed. System administrators should also implement email filtering mechanisms that limit the size of incoming messages and sanitize HTML content before processing. Network-level controls such as rate limiting and message size restrictions can help prevent exploitation while patches are being deployed. Additionally, monitoring systems should be configured to detect unusual cpu utilization patterns that may indicate exploitation attempts. Organizations should consider implementing input validation and sanitization measures for all email processing components, following security best practices outlined in standards such as the CWE-1314 category for regular expression vulnerabilities and ATT&CK technique T1499 for denial of service attacks. The remediation process should include comprehensive testing of patched systems to ensure that the vulnerability has been properly addressed without introducing regressions in system functionality.