CVE-2012-3447 in Nova
Summary
by MITRE
virt/disk/api.py in OpenStack Compute (Nova) 2012.1.x before 2012.1.2 and Folsom before Folsom-3 allows remote authenticated users to overwrite arbitrary files via a symlink attack on a file in an image that uses a symlink that is only readable by root. NOTE: this vulnerability exists because of an incomplete fix for CVE-2012-3361.
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Analysis
by VulDB Data Team • 12/12/2021
The vulnerability described in CVE-2012-3447 represents a critical file system permission issue within OpenStack Compute (Nova) that emerged from an incomplete remediation of a previous security flaw. This vulnerability specifically affects the virt/disk/api.py component in OpenStack Nova versions 2012.1.x prior to 2012.1.2 and the Folsom release before Folsom-3. The core issue stems from inadequate handling of symbolic links during image processing operations, creating a scenario where authenticated attackers can exploit file system permissions to overwrite arbitrary files on the system. The vulnerability is particularly dangerous because it leverages the privilege escalation potential inherent in symlink attacks, allowing attackers to manipulate file operations that should be restricted to root-level access.
The technical flaw manifests when OpenStack Nova processes disk images that contain symbolic links, particularly those that point to files only readable by the root user. During the image processing workflow, the system fails to properly validate or sanitize these symbolic links, creating a race condition or permission bypass scenario. Attackers can craft malicious disk images containing carefully constructed symbolic links that, when processed by Nova, result in the unintended overwriting of critical system files or sensitive data. This occurs because the underlying file system operations do not adequately verify the target destinations of symbolic links or enforce proper access controls during the image processing lifecycle. The vulnerability specifically exploits the difference between the permissions of the user running the Nova service and the root-level permissions required to access certain system files.
The operational impact of this vulnerability extends beyond simple file overwrites to potentially enable broader system compromise and privilege escalation attacks. Remote authenticated users who can upload or modify disk images within the OpenStack environment can leverage this vulnerability to gain unauthorized access to system resources, modify critical system files, or potentially establish persistent backdoors. The attack vector is particularly concerning in multi-tenant cloud environments where different users share the same infrastructure, as it allows one user to potentially compromise the entire system or other users' resources. This vulnerability can be exploited to overwrite configuration files, system binaries, or sensitive data files, potentially leading to complete system compromise or data exfiltration. The risk is amplified by the fact that this vulnerability was introduced by an incomplete fix for CVE-2012-3361, indicating a pattern of flawed security remediation that could lead to additional related vulnerabilities.
The vulnerability aligns with CWE-59 and CWE-22 categories, specifically addressing issues related to improper handling of symbolic links and path traversal attacks. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation through file system manipulation and credential access through exploitation of system vulnerabilities. Organizations should implement immediate mitigations including updating to patched versions of OpenStack Nova, implementing strict image validation policies, and ensuring proper file system permissions are enforced during image processing operations. The complete remediation requires not only updating the software but also implementing additional security controls such as mandatory access controls, enhanced file system monitoring, and regular security audits of image processing workflows. This vulnerability serves as a critical reminder of the importance of thorough security testing and the potential risks associated with incomplete vulnerability fixes in complex cloud infrastructure systems.