Suspicious Modification of Ivanti lastauthserverused.js for Credential Harvesting

ATT&CK techniques

Cred Access

Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
- T1552.001Credentials In Files
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule detects modification of the Ivanti Connect Secure lastauthserverused.js file which attackers weaponized to base64 encode and capture credentials submitted to the VPN login page. This was observed during exploitation of Ivanti Connect Secure zero-day vulnerabilities. Capturing plaintext credentials at the gateway enables lateral movement and long-term access.

Reporting behind it

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Suspicious Modification of Ivanti lastauthserverused.js for Credential Harvesting

Pivot detection · T1552.001 · 9 related

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

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