CVE-2011-0401 in Piwik
Summary
by MITRE
Piwik before 1.1 does not properly limit the number of files stored under tmp/sessions/, which might allow remote attackers to cause a denial of service (inode consumption) by establishing many sessions.
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Analysis
by VulDB Data Team • 10/11/2021
The vulnerability identified as CVE-2011-0401 affects Piwik versions prior to 1.1, specifically targeting the temporary session storage mechanism within the application's file system structure. This flaw resides in the tmp/sessions/ directory where session files are created and maintained during user interactions with the analytics platform. The issue stems from inadequate session management controls that fail to enforce proper limits on the number of session files that can be generated and stored within this critical temporary directory. Attackers can exploit this weakness by creating an excessive number of session files, leading to resource exhaustion and ultimately disrupting the availability of the service.
The technical implementation of this vulnerability demonstrates a classic denial of service attack vector through inode exhaustion. When Piwik creates session files in the tmp/sessions/ directory without proper constraints on session file creation, each authenticated user or malicious actor can generate multiple session files that persist in the file system. As these session files accumulate without proper cleanup mechanisms or size limitations, they consume available inodes on the file system. Inodes are data structures that store metadata about files and directories, and when exhausted, the system cannot create new files or directories, effectively causing a denial of service condition that impacts legitimate users and system operations.
This vulnerability directly maps to CWE-400, which describes improper restriction of automated handling of a resource, specifically in the context of resource exhaustion. The flaw represents a failure in resource management where the application does not adequately control the consumption of file system resources through session file creation. From an operational perspective, this vulnerability creates significant risk for organizations relying on Piwik for web analytics, as it allows remote attackers to disrupt service availability without requiring elevated privileges or complex exploitation techniques. The attack can be executed by simply establishing multiple sessions, making it particularly dangerous in environments where automated tools or bots might be leveraged to amplify the impact.
The impact of this vulnerability extends beyond simple service disruption to encompass broader security implications for system stability and availability. Organizations using vulnerable Piwik installations face potential business disruption as legitimate users experience service degradation or complete unavailability of the analytics platform. The resource exhaustion occurs at the file system level, meaning that even if the application itself remains functional, the underlying storage system becomes incapable of handling new session requests. This creates cascading effects that can impact other applications sharing the same file system or storage resources.
Mitigation strategies for CVE-2011-0401 should focus on implementing proper session management controls and resource limiting mechanisms. Organizations should immediately upgrade to Piwik version 1.1 or later, which includes fixed session handling logic that properly limits the number of session files created and maintains appropriate cleanup procedures. System administrators should also implement monitoring for unusual session file creation patterns and establish automated cleanup processes for temporary directories. Additionally, implementing file system quotas and limits on the tmp/sessions/ directory can provide additional protection against similar vulnerabilities. The ATT&CK framework categorizes this type of vulnerability under T1499, which covers resource exhaustion techniques, highlighting the importance of proper resource management and access controls in preventing such denial of service scenarios.