Suspicious Oversized Numeric X-Forwarded-For Header Targeting Ivanti Connect Secure (via proxy)

ATT&CK techniques

Initial Access

Recon
Resource Dev
Initial Access
- T1190Exploit Public-Facing Application
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule detects the network signature of Ivanti Connect Secure CVE-2025-22457 where an extremely long X-Forwarded-For header consisting only of digits and periods is used to overflow a stack buffer in the web process. Legitimate proxy chains do not produce headers of this length.

Reporting behind it

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Suspicious Oversized Numeric X-Forwarded-For Header Targeting Ivanti Connect Secure (via proxy)

Pivot detection · T1190 · 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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