CVE-2014-8325 in Calender Base
Summary
by MITRE
The Calendar Base (cal) extension before 1.5.9 and 1.6.x before 1.6.1 for TYPO3 allows remote attackers to cause a denial of service (resource consumption) via vectors related to the PHP PCRE library.
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Analysis
by VulDB Data Team • 12/09/2024
The vulnerability identified as CVE-2014-8325 affects the Calendar Base extension within TYPO3 content management systems, specifically targeting versions prior to 1.5.9 and 1.6.x versions before 1.6.1. This issue represents a significant security concern as it enables remote attackers to execute denial of service attacks by exploiting weaknesses in the PHP PCRE library integration within the calendar extension. The affected TYPO3 versions utilize regular expression processing capabilities that become vulnerable when handling specific input patterns, creating a pathway for resource exhaustion attacks.
The technical flaw stems from improper handling of regular expression patterns within the calendar extension's processing logic. When the extension processes calendar-related data, it relies on PHP's PCRE (Perl Compatible Regular Expressions) library for pattern matching and data parsing. Attackers can craft malicious input sequences that trigger excessive backtracking in the PCRE engine, causing the system to consume disproportionate amounts of CPU cycles and memory resources. This particular vulnerability aligns with CWE-129, which describes improper validation of regular expression special characters, and represents a classic example of a regular expression denial of service attack.
The operational impact of this vulnerability extends beyond simple service disruption, as it can effectively render TYPO3 installations unusable for legitimate users. When exploited, the vulnerability causes the web server to consume excessive computational resources, potentially leading to complete system unresponsiveness or server crashes. This type of attack can be particularly devastating in production environments where calendar functionality is critical for business operations. The resource consumption pattern typically manifests as sustained high CPU utilization and memory allocation, making it difficult for administrators to distinguish from legitimate high-traffic conditions. Organizations running affected TYPO3 installations face potential business disruption and may experience cascading effects on other services that depend on the same infrastructure.
Mitigation strategies for this vulnerability involve immediate patching of the Calendar Base extension to versions 1.5.9 or 1.6.1 and later, which contain the necessary code modifications to prevent the problematic regular expression patterns from being processed. System administrators should also implement input validation measures at the web application firewall level to detect and block suspicious pattern matching sequences before they reach the vulnerable extension. Additionally, monitoring systems should be configured to alert administrators when unusual resource consumption patterns occur, enabling rapid response to potential exploitation attempts. The remediation process should include thorough testing of the patched extension to ensure that legitimate calendar functionality remains intact while addressing the resource consumption vulnerability. Organizations should also consider implementing rate limiting and resource allocation controls to minimize the impact of any potential exploitation attempts. This vulnerability demonstrates the importance of regular security updates and proper input validation practices in preventing resource exhaustion attacks that can compromise system availability.