CVE-2020-12463 in Software Updater
Summary
by MITRE
An elevation of privilege vulnerability exists in Avira Software Updater before 2.0.6.27476 due to improperly handling file hard links. This allows local users to obtain take control of arbitrary files.
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Analysis
by VulDB Data Team • 10/15/2020
The vulnerability identified as CVE-2020-12463 represents a critical elevation of privilege flaw within Avira Software Updater versions prior to 2.0.6.27476. This security weakness stems from inadequate handling of file hard links during the software update process, creating a significant attack surface that malicious local users can exploit to gain unauthorized control over arbitrary files on the system. The flaw specifically manifests when the updater component processes file operations that involve hard links, which are multiple directory entries referring to the same inode on a filesystem. The improper implementation fails to validate or properly manage these hard link scenarios, allowing attackers to manipulate the update mechanism to overwrite or modify files that they would normally not have access to modify.
The technical exploitation of this vulnerability occurs through the manipulation of file hard links within the update process, which is classified under CWE-264 as "Permissions, Privileges, and Access Controls." The flaw enables attackers to leverage the legitimate update functionality to achieve unauthorized file system modifications by creating or exploiting hard link relationships that bypass normal access controls. When the Avira updater processes updates, it does not adequately distinguish between legitimate file operations and malicious hard link manipulations, allowing an attacker to place a hard link to a protected file within the update directory structure. This creates a situation where file operations intended for legitimate updates can instead result in modification of system-critical files or files belonging to other users. The vulnerability operates at the intersection of file system security and software update mechanisms, making it particularly dangerous as it leverages the trust associated with legitimate software update processes.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it enables attackers to potentially compromise the integrity of the entire system through file manipulation. Local users who can execute code on the target system can exploit this flaw to modify critical system files, configuration files, or even executable components that are protected by normal file permissions. This capability can lead to persistent access, data corruption, or further exploitation opportunities that could compromise the confidentiality, integrity, and availability of the affected system. The attack vector is particularly concerning because it requires only local user access, meaning that any user account with basic system privileges could potentially exploit this vulnerability. From an attacker's perspective, this flaw aligns with techniques described in the MITRE ATT&CK framework under privilege escalation tactics, specifically targeting the "Exploitation for Privilege Escalation" technique where attackers leverage software vulnerabilities to gain higher system privileges.
The remediation for CVE-2020-12463 requires immediate deployment of Avira Software Updater version 2.0.6.27476 or later, which includes proper handling of file hard links during the update process. System administrators should verify that all affected systems have been patched and monitor for any unusual file system activity that might indicate exploitation attempts. The fix implemented by Avira addresses the core issue by ensuring that hard links are properly validated and handled during file operations, preventing the creation of malicious link relationships that could be exploited for privilege escalation. Organizations should also implement additional security measures such as monitoring for unauthorized file modifications, maintaining up-to-date antivirus signatures, and ensuring that software update mechanisms are properly configured with appropriate access controls. The vulnerability highlights the importance of proper file system handling in security-critical applications and demonstrates how seemingly minor implementation flaws in update mechanisms can create significant security risks. Regular security assessments of update processes and file system operations should be conducted to identify similar vulnerabilities in other software components, particularly those that handle file operations with elevated privileges or perform system modifications.