CVE-2011-1550 in logrotate
Summary
by MITRE
The default configuration of logrotate on SUSE openSUSE Factory uses root privileges to process files in directories that permit non-root write access, which allows local users to conduct symlink and hard link attacks by leveraging logrotate s lack of support for untrusted directories, as demonstrated by directories for the (1) cobbler, (2) inn, (3) safte-monitor, and (4) uucp packages.
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Analysis
by VulDB Data Team • 05/25/2017
The vulnerability described in CVE-2011-1550 represents a critical privilege escalation flaw within the logrotate utility on SUSE openSUSE Factory systems. This issue stems from the default configuration where logrotate executes with root privileges while processing log files in directories that allow non-root users to write files. The fundamental technical flaw lies in logrotate's inability to properly handle untrusted directories during its execution cycle, creating a dangerous environment where malicious users can manipulate the system through symbolic link and hard link attacks.
The operational impact of this vulnerability is significant as it provides local attackers with a pathway to escalate privileges from their current user level to root access. Attackers can exploit this by creating malicious symbolic links or hard links within the targeted directories used by logrotate, specifically those associated with cobbler, inn, safte-monitor, and uucp packages. When logrotate processes these manipulated files, it follows the symbolic links or hard links and executes commands with elevated privileges, effectively allowing unauthorized users to gain root access to the system. This vulnerability directly relates to CWE-264, which addresses permissions, privileges, and access controls, specifically focusing on the improper handling of privilege escalation opportunities.
The attack vector demonstrates a classic case of privilege escalation through file system manipulation, where the attacker leverages the trust model inherent in logrotate's operation. The system assumes that files in directories it processes are safe and trustworthy, but this assumption fails when non-root users can modify directory contents. This vulnerability aligns with ATT&CK technique T1068, which covers 'Exploitation for Privilege Escalation', and specifically targets the 'Exploitation of a Software Vulnerability' sub-technique. The exploitation requires minimal privileges to create symbolic links or hard links in the targeted directories, making it particularly dangerous as it can be executed by any local user with write access to these specific directories.
Mitigation strategies for this vulnerability involve several approaches that address the root cause of the issue. The most effective solution is to configure logrotate to avoid processing files in directories that allow non-root write access, which can be achieved through careful configuration of logrotate's include and exclude directives. System administrators should also implement proper directory permissions and access controls to prevent unauthorized modifications to log directories. Additionally, regular security audits should verify that logrotate configurations do not inadvertently process files in untrusted locations. The recommended approach includes implementing proper file system permissions, using secure directory structures, and ensuring that logrotate operates in a controlled environment where it cannot be easily manipulated by local users. Organizations should also consider implementing monitoring solutions to detect unusual file system activities in log directories and establish regular patch management procedures to ensure timely updates of logrotate and related system components.