CVE-2018-6693 in ENSLTP
Summary
by MITRE
An unprivileged user can delete arbitrary files on a Linux system running ENSLTP 10.5.1, 10.5.0, and 10.2.3 Hotfix 1246778 and earlier. By exploiting a time of check to time of use (TOCTOU) race condition during a specific scanning sequence, the unprivileged user is able to perform a privilege escalation to delete arbitrary files.
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Analysis
by VulDB Data Team • 05/17/2023
The vulnerability described in CVE-2018-6693 represents a critical privilege escalation flaw within ENSLTP (Enterprise Network Security Layer Threat Prevention) versions 10.5.1, 10.5.0, and 10.2.3 Hotfix 1246778 and earlier. This issue arises from a time of check to time of use race condition that allows unprivileged users to manipulate file system operations during specific scanning sequences, ultimately enabling them to delete arbitrary files on the target Linux system. The vulnerability specifically impacts systems where ENSLTP is installed and running with elevated privileges, creating a dangerous scenario where user-level access can be leveraged to perform system-level destructive actions.
The technical implementation of this vulnerability stems from improper synchronization mechanisms during file access validation within the scanning process. During the scanning sequence, the system performs a check to determine if a file can be accessed or modified, but this validation occurs at a different point in time than the actual file operation. An attacker can exploit this temporal gap by creating a symbolic link or manipulating file paths between the validation check and the actual file deletion operation. This race condition allows the attacker to redirect the file deletion operation to target files that should normally be protected, effectively bypassing access controls and privilege restrictions. The flaw aligns with CWE-367, which specifically addresses Time-of-Check to Time-of-Use race conditions, and demonstrates how inadequate temporal consistency in security checks can lead to severe privilege escalation vulnerabilities.
The operational impact of this vulnerability extends beyond simple file deletion capabilities, as it fundamentally undermines the security model of the affected systems. An unprivileged user who gains access to the system can leverage this flaw to remove critical system files, configuration data, or even malicious software components that would normally require administrative privileges to delete. This capability can lead to system instability, data loss, or the complete compromise of the affected system's integrity. The vulnerability is particularly concerning because it operates at the kernel or system level where the scanning process runs with elevated privileges, making the attack vector extremely potent. Attackers can use this vulnerability to remove security logs, disable security features, or corrupt system files to maintain persistence or cause denial of service conditions.
Mitigation strategies for CVE-2018-6693 should focus on both immediate patching and operational hardening measures. Organizations must immediately upgrade to ENSLTP versions that have addressed this vulnerability, as vendors typically release patches that correct the race condition through proper synchronization mechanisms or by eliminating the temporal gap in file access validation. System administrators should also implement additional monitoring to detect suspicious file deletion patterns and ensure that the scanning processes run with minimal necessary privileges. The ATT&CK framework categorizes this type of vulnerability under privilege escalation techniques, specifically targeting the T1068 entry for "Exploitation for Privilege Escalation." Security teams should also consider implementing file integrity monitoring solutions and ensuring proper file system permissions are enforced, particularly around directories that may be accessed during scanning operations. Additionally, network segmentation and least privilege principles should be enforced to limit the potential impact of such vulnerabilities within the broader infrastructure.