Detection of Windows Time-Based Evasion via Ping Delays

This threat brief focuses on an evasion technique frequently observed in malware such as NjRAT and BlankGrabber. Attackers use the command-line utility 'ping.exe' to execute a ping request against an invalid IP address (often '0'). By including a wait count via the '-n' flag, the malware induces a deliberate timeout, causing the operating system to pause execution of subsequent commands. This tactic is used to thwart automated sandbox analysis - which often has time-limited inspection windows - and to synchronize the self-deletion of dropper files or secondary payloads. Defenders should monitor for instances where 'ping.exe' is invoked with these specific command-line arguments, as it rarely appears in standard administrative or system processes.

Attack Chain

1. Initial infection via delivery of a malicious dropper (e.g., NjRAT or BlankGrabber).
2. Execution of the primary malicious payload on the target system.
3. Malware prepares to perform secondary actions (e.g., establishing persistence or downloading additional modules).
4. Execution of 'ping.exe 0 -n [count]' to initiate a synthetic execution delay.
5. The system process pauses while waiting for the invalid network request to time out.
6. Malware proceeds to self-delete the original dropper binary to remove forensic artifacts.
7. Malware executes secondary payloads or establishes C2 communication after the delay.

Impact

Successful use of this evasion technique allows malicious software to evade automated security sandboxes, increasing the likelihood of successful deployment and persistence within the environment. If the delay is timed effectively, the attacker successfully removes the primary installation vector (the dropper), complicating incident response and forensic analysis.

Recommendation

1. Enable Sysmon Event ID 1 (Process Creation) across all Windows endpoints to capture full command-line arguments.
2. Implement the Sigma rule provided in this brief to alert on 'ping.exe' executions containing '0 -n' patterns.
3. Tune security monitoring to exclude known-benign administrative scripts if any are discovered to use this syntax for network latency measurement, though this is highly atypical.
4. Integrate EDR telemetry into a SIEM using the CIM to ensure 'Processes.process' and 'Processes.parent_process' fields are consistently populated and searchable.