CVE-2011-2772 in Mahara
Summary
by MITRE
The get_dataroot_image_path function in lib/file.php in Mahara before 1.4.1 does not properly validate uploaded image files, which allows remote attackers to cause a denial of service (memory consumption) via a (1) large or (2) invalid image.
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Analysis
by VulDB Data Team • 11/26/2021
The vulnerability identified as CVE-2011-2772 affects the Mahara learning management system version 1.4.0 and earlier, specifically within the file handling component that processes uploaded images. This flaw resides in the get_dataroot_image_path function located in the lib/file.php file, which represents a critical security oversight in the application's input validation mechanisms. The vulnerability stems from insufficient validation of image file properties during the upload process, creating a pathway for malicious actors to exploit the system through crafted image files.
The technical implementation of this vulnerability demonstrates a classic case of inadequate input sanitization where the system fails to properly validate the characteristics of uploaded image files before processing them. Attackers can leverage this weakness by uploading either extremely large image files or malformed image data that causes the application to consume excessive memory resources during processing. The vulnerability manifests when the system attempts to handle these malformed inputs without proper bounds checking or file format verification, leading to memory exhaustion and subsequent denial of service conditions. This type of vulnerability aligns with CWE-20, which addresses improper input validation, and represents a common pattern in web applications where file upload handlers lack sufficient security controls.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise the entire availability of the Mahara platform. When exploited, the denial of service condition can consume all available memory resources on the server hosting the application, causing legitimate users to be unable to access the system and potentially leading to complete system unavailability. This vulnerability affects the core functionality of the learning management system and can be particularly damaging in educational environments where continuous access to learning materials is essential. The attack vector is particularly concerning as it requires no authentication and can be executed remotely, making it accessible to any attacker with network access to the vulnerable system.
Mitigation strategies for CVE-2011-2772 should focus on implementing comprehensive file validation mechanisms that enforce strict size limits and format verification for all uploaded images. Organizations should immediately upgrade to Mahara version 1.4.1 or later, which contains the necessary patches to address this vulnerability. Additional protective measures include implementing file size restrictions, validating image headers and metadata, and deploying content delivery network configurations that can detect and block malicious file uploads. The vulnerability also highlights the importance of following secure coding practices as outlined in the OWASP Top Ten and MITRE ATT&CK framework, specifically addressing the techniques related to resource exhaustion attacks and input validation failures. System administrators should also consider implementing intrusion detection systems that can monitor for unusual memory consumption patterns and automated file upload activities that may indicate exploitation attempts.