CVE-2012-1588 in Drupal
Summary
by MITRE
Algorithmic complexity vulnerability in the _filter_url function in the text filtering system (modules/filter/filter.module) in Drupal 7.x before 7.14 allows remote authenticated users with certain roles to cause a denial of service (CPU consumption) via a long email address.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 12/14/2021
The vulnerability identified as CVE-2012-1588 represents a critical algorithmic complexity issue within Drupal 7.x text filtering mechanisms, specifically targeting the _filter_url function in the filter.module file. This flaw exists in Drupal versions prior to 7.14 and demonstrates a classic example of a denial of service attack through resource exhaustion. The vulnerability is particularly concerning because it can be exploited by authenticated users who possess specific roles within the Drupal system, making it a significant threat to web application availability. The attack vector involves crafting maliciously long email addresses that trigger inefficient processing within the text filtering subsystem, causing excessive cpu consumption that can ultimately lead to system unresponsiveness or complete service disruption.
The technical root cause of this vulnerability lies in the inefficient implementation of the _filter_url function which processes email addresses through a regular expression pattern matching algorithm. When an attacker submits an email address of substantial length, the function's processing becomes increasingly complex and computationally expensive, creating a time complexity issue that scales poorly with input size. This algorithmic inefficiency allows an attacker to consume disproportionate system resources relative to the input size, effectively creating a resource exhaustion scenario. The vulnerability is classified as a weakness in the software's input validation and processing logic, specifically within the text filtering system that is designed to sanitize user content before display. According to CWE standards, this represents a weakness in the implementation of string processing algorithms where the computational complexity is not properly bounded, making it susceptible to algorithmic complexity attacks.
The operational impact of CVE-2012-1588 extends beyond simple service disruption to potentially compromise the entire web application availability. When exploited, this vulnerability can cause significant cpu consumption that may affect other system processes, leading to cascading failures in web application performance. The attack is particularly effective because it requires minimal privileges - only authenticated users with specific roles need to be compromised, making it more accessible than attacks requiring administrative access. This vulnerability can be particularly damaging in high-traffic environments where the denial of service could impact many users simultaneously. The attack can be executed repeatedly and systematically, allowing attackers to maintain their denial of service condition until system resources are exhausted or the application is manually restarted. From an attacker's perspective, this vulnerability provides a reliable method to disrupt service without requiring sophisticated tools or extensive knowledge of the underlying system architecture.
Mitigation strategies for CVE-2012-1588 primarily focus on applying the official security patch released by Drupal, specifically version 7.14 which includes fixes to the _filter_url function. System administrators should immediately upgrade their Drupal installations to version 7.14 or later to eliminate this vulnerability. Additional protective measures include implementing input validation controls that limit the maximum length of email addresses processed by the text filtering system, thereby preventing the exploitation of the algorithmic complexity issue. Network-level protections such as rate limiting and request size restrictions can provide additional defense-in-depth measures, though these are secondary to the core patching requirement. The vulnerability highlights the importance of proper algorithmic complexity analysis during software development, particularly for functions that process user-supplied input. Organizations should implement comprehensive security testing that includes performance and resource consumption analysis to identify similar algorithmic complexity vulnerabilities. From an att&ck framework perspective, this vulnerability aligns with the defense evasion and resource exhaustion tactics, demonstrating how seemingly benign text processing functions can become attack vectors when poorly implemented. Regular security audits and vulnerability assessments should specifically target text processing and filtering components to prevent similar issues from emerging in the future.