Wevtutil.exe, a Windows tool for event log management, offers powerful features like exporting, clearing, and querying logs. While essential for system administration, malicious actors can exploit these capabilities to conceal their activities or steal sensitive data.
By exporting logs to XML format, attackers can extract valuable information, where clearing logs can help them remove incriminating evidence.
And by querying logs, they can identify specific events of interest, as this dual-use nature of wevtutil.exe highlights the importance of securing systems and monitoring for suspicious activity.
It is a native Windows tool and can be leveraged in Living-off-the-Land Binaries and Scripts (LOLBAS) attacks, where attackers can exploit wevtutil to selectively clear event logs, such as the Application log, to hinder incident response efforts.
By clearing logs, attackers can obscure their tracks and make it difficult to identify and investigate malicious activities, which, coupled with the use of a less common tool like wevtutil, can bypass traditional security measures that rely on detecting common attack methods.
When it comes to clearing the security log, the wevtutil command is less stealthy because it does not have the capability to selectively clear specific events that are contained within an event log.
Clearing the Security log triggers Event ID 1102, which exposes the clearing action’s details, including the user and process, which makes it less attractive for attackers seeking to evade detection.
While clearing non-Security logs like Application or System doesn’t generate such logs by default, enabling Audit Policies can track log clearing activities, enhancing security monitoring and incident response capabilities.
To enhance security, enable auditing of object access events via Group Policy, which prevents unauthorized clearing of event logs and could hinder incident investigation.
Malicious actors may use tools like `wevtutil.exe` to exfiltrate sensitive information from event logs. While standard users are restricted, elevated privileges can bypass these controls, emphasizing the need for strong access controls and monitoring.
Administrators and users with read access can export logs, which are often restricted, while application/system logs can be more accessible, as Wevtutil.exe enables detailed log querying, allowing attackers to gather sensitive information.
Standard users lack the necessary privileges to execute such queries. However, elevated privileges grant access, enabling attackers to analyze user activity patterns through logon events.
To mitigate the risks associated with wevtutil.exe abuse, organizations should implement enhanced monitoring for its usage, especially focusing on unusual commands like `cl` and `qe`.
According to Denwp research, strict access controls should be enforced to prevent unauthorized clearing or exporting of event logs, while centralized log aggregation can ensure redundancy and anomaly detection.
Leveraging behavioral analytics to identify patterns consistent with LOLBAS techniques, such as combinations of tools like wevtutil.exe, makecab.exe, and certutil.exe, can further strengthen security posture.
