CVE-2017-8108 in Lynis
Summary
by MITRE
Unspecified tests in Lynis before 2.5.0 allow local users to write to arbitrary files or possibly gain privileges via a symlink attack on a temporary file.
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Analysis
by VulDB Data Team • 08/23/2024
The vulnerability identified as CVE-2017-8108 affects Lynis, a security auditing tool widely used for system hardening and compliance verification. This issue exists in versions prior to 2.5.0 and represents a critical security flaw that can be exploited by local attackers to manipulate system files or escalate privileges. The vulnerability stems from insufficient validation of temporary files created during the execution of various security tests within the Lynis framework.
The technical flaw manifests through a symlink attack vector that exploits the insecure handling of temporary files during test execution. When Lynis performs its security checks, it creates temporary files in predictable locations without proper validation of symbolic links. Local attackers can create malicious symbolic links that point to sensitive system files or directories, allowing them to write arbitrary content to locations that should remain protected. This behavior aligns with CWE-377, which addresses insecure temporary file handling, and specifically relates to CWE-59, which covers improper handling of symbolic links.
The operational impact of this vulnerability extends beyond simple file manipulation, as it can potentially lead to privilege escalation depending on how the affected Lynis tests are executed. Attackers who gain access to a system with Lynis installed can leverage this flaw to modify critical system files, potentially compromising the integrity of the security auditing process itself. The vulnerability is particularly concerning because Lynis is often run with elevated privileges during security audits, making the potential for privilege escalation more severe. This attack vector can be classified under ATT&CK technique T1059.007 for execution through scripts and T1068 for privilege escalation through local exploitation.
The exploitation requires local access to the system and involves creating carefully crafted symbolic links in directories where Lynis creates temporary files. This attack is considered relatively straightforward to execute, as it does not require network access or complex preconditions. The vulnerability affects systems where Lynis is installed and regularly used for security assessments, particularly in enterprise environments where system hardening is critical. Organizations using older versions of Lynis should immediately consider upgrading to version 2.5.0 or later, which includes proper validation of temporary file creation and handling mechanisms. Additionally, system administrators should review the execution permissions and file ownership of Lynis temporary directories to minimize potential impact from this class of vulnerability.