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Cisco NVM - Curl Execution With Insecure Flags

This analytic detects the use of `curl.exe` with insecure flags such as `-k`, `--insecure`, `--proxy-insecure`, or `--doh-insecure` which disable TLS certificate validation. It leverages Cisco Network Visibility…

Description

This analytic detects the use of `curl.exe` with insecure flags such as `-k`, `--insecure`, `--proxy-insecure`, or `--doh-insecure` which disable TLS certificate validation. It leverages Cisco Network Visibility Module (NVM) flow data and process arguments to identify outbound connections initiated by curl where TLS checks were explicitly disabled. This behavior may indicate an attempt to bypass certificate validation to connect to potentially untrusted or malicious endpoints, a common tactic in red team operations, malware staging, or data exfiltration over HTTPS.

Detection logic

Detection requirements

Platform
Windows

The rule states no platform. This is derived from the ATT&CK technique it maps to.

Known benign triggers

  • Usage of these flags to reach public IPs or uncommon destinations should be reviewed. Tuning may be required for domains with known certificate issues.

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