Potential Network Sniffing via Start-NetEventSession

Attackers may abuse the built-in Windows PowerShell cmdlet 'Start-NetEventSession' to initiate unauthorized packet capture on a compromised host. This technique, classified as Network Sniffing (T1040), allows an adversary to monitor network traffic for sensitive information, such as plaintext credentials, configuration data, or internal network topology details. By leveraging native administrative tools, actors can often bypass legacy security controls that rely on signature-based detection of third-party sniffing utilities like Wireshark or tcpdump. Defenders should monitor PowerShell Script Block logs for the invocation of this cmdlet to identify post-exploitation sniffing activity. This detection is particularly critical in environments where unencrypted protocols are still in use, as the impact of such sniffing can lead to widespread credential compromise.

Impact

Successful exploitation allows attackers to gain visibility into internal network communications, potentially leading to the interception of sensitive data, authentication tokens, and user credentials transmitted via insecure protocols. This provides a foundation for lateral movement and further escalation of privileges within the victim's environment.

Recommendation

• Enable PowerShell Script Block Logging (Event ID 4104) across all Windows endpoints to ensure visibility into cmdlet execution.
• Deploy the provided Sigma rule to detect the use of Start-NetEventSession and triage alerts against known network administration baselines.
• Audit administrative usage of network diagnostic tools to establish a baseline of expected behavior and reduce false positives from authorized IT operations.