Detect Check Point Security Gateway Improper Authentication (CVE-2026-50751) in Elastic Security
Detects exploitation of CVE-2026-50751, an improper authentication vulnerability (CWE-287) in Check Point Security Gateway affecting deprecated IKEv1 VPN protocol. This vulnerability is actively exploited in the wild (CISA KEV) and may allow unauthenticated attackers to bypass authentication controls on the VPN gateway. Detection focuses on anomalous IKEv1 negotiation patterns, authentication bypass indicators, and suspicious gateway access following failed or malformed IKE exchanges.
MITRE ATT&CK
- Tactic
- Initial Access Credential Access
Elastic Detection Query
sequence by source.ip with maxspan=10m
[network where event.dataset == "checkpoint.firewall"
and (message like~ "*IKEv1*" or message like~ "*aggressive mode*" or message like~ "*ikev1*")
and destination.port in (500, 4500)]
[network where event.dataset == "checkpoint.firewall"
and (event.action like~ "*auth*" or message like~ "*authentication*" or message like~ "*bypass*")
and (event.outcome == "failure" or message like~ "*failed*" or message like~ "*unauthenticated*")]EQL sequence rule detecting IKEv1 negotiation followed by authentication anomaly from the same source IP on Check Point Security Gateway, indicative of CVE-2026-50751 exploitation attempts.
Data Sources
Required Tables
False Positives & Tuning
- Legitimate dual-stack VPN endpoints retrying with IKEv1 after IKEv2 failure
- Network monitoring appliances performing IKEv1 health checks on the gateway
- Authorized red team exercises simulating VPN protocol downgrade attacks
Other platforms for CVE-2026-50751
Testing Methodology
Validate this detection against 3 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1IKEv1 Aggressive Mode Probe — Check Point Gateway
Expected signal: Check Point SmartLog IKE phase 1 event with protocol IKEv1, mode aggressive, from the test host IP. UDP/500 connection event in network logs.
- Test 2Repeated IKEv1 Auth Failure Simulation
Expected signal: 10 IKEv1 negotiation attempts with authentication failure events in SmartLog. Source IP flagged in Check Point IPS/firewall blade logs.
- Test 3IKEv1 vs IKEv2 Protocol Downgrade Attempt
Expected signal: StrongSwan IKEv1 initiation attempt visible in system logs; Check Point gateway logs showing inbound IKEv1 proposal from test host on UDP/500.
Unlock Pro Content
Get the full detection package for CVE-2026-50751 including response playbook, investigation guide, and atomic red team tests.