Suspicious AiTM Phishing Kit Session Validation Endpoint via Proxy

ATT&CK techniques

Cred Access → Collection

Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
- T1557Adversary-in-the-Middle
C2
Exfiltration
Impact

What it detects

This rule detects web requests to reverse-proxy adversary-in-the-middle phishing kit endpoints, specifically the check_response handler carrying a session_id parameter alongside kit paths such as api/login, 2fa, sms and tap. It is associated with the Operation Fake KickOff campaign that abused recruiters and SaaS services to harvest corporate credentials and relay multi-factor authentication tokens. Detecting these structured kit paths surfaces live credential and MFA session theft.

Reporting behind it

Related detections9 linkedT1557 — drag to rearrange

Malicious Tycoon 2FA AiTM Phishing WebSocket Channel

Suspicious Sneaky 2FA Phishing Kit License Check via API Key Endpoint (via proxy)

Malicious TCP Session Hijacking via rshijack

Suspicious Entra ID Device Code Flow Authentication

Suspicious Entra ID Auth Broker Sign-In With Node.js User Agent via Tycoon 2FA

Malicious EdgeStepper iptables DNS Redirection for Adversary-in-the-Middle

Suspicious Tycoon 2FA Credential Exfiltration Fields

Suspicious Entra Sign-In to OfficeHome with axios User Agent

Suspicious Entra Sign-In Interrupt With High Aggregated Risk via AiTM DNS Hijacking (via azure)

Suspicious AiTM Phishing Kit Session Validation Endpoint via Proxy

Pivot detection · T1557 · 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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