UnknownPublished 23 Jan 2026

tlp clear · KRVTZ IDS alerts for 2026-01-23

Affects tlp clearSource CIRCL OSINT Feed

TLP:CLEAR, disclosure is not limited

Mentions 1 CVE

Mentioned vulnerabilities

CVE-2023-27997

Description

KRVTZ IDS alerts for 2026-01-23

Impact

For European organizations, the primary impact of these KRVTZ IDS alerts lies in the potential exposure of Fortigate VPN appliances to reconnaissance and exploitation attempts targeting CVE-2023-27997. Successful exploitation could lead to unauthorized access or denial of service, compromising the confidentiality, integrity, and availability of VPN services critical for secure remote access. Given the widespread use of Fortigate VPNs across Europe, particularly in sectors reliant on secure remote connectivity such as finance, government, and critical infrastructure, these scanning activities could signal preparatory steps for more targeted attacks. Although the current threat level is low, failure to detect and mitigate such reconnaissance could increase the risk of subsequent breaches. Additionally, the presence of scanning IPs using fake Windows NT user agents may indicate broader automated scanning campaigns that could identify other vulnerabilities or misconfigurations in European networks. The impact is thus primarily on network security posture and the potential for increased attack surface exposure if proactive measures are not taken.

Defensive guidance

European organizations should implement specific mitigations beyond generic advice to address this threat effectively. First, ensure all Fortigate VPN appliances are updated to the latest firmware versions that include patches for CVE-2023-27997 to eliminate the vulnerability exploited by repeated GET requests to /remote/logincheck. Deploy and fine-tune intrusion detection and prevention systems (IDS/IPS) to recognize and block scanning patterns associated with fake Windows NT user agents and repeated logincheck requests. Implement strict access controls and network segmentation to limit exposure of VPN endpoints to the internet, ideally restricting access to known IP ranges or via VPN gateways with multi-factor authentication. Monitor network logs for unusual or repeated access attempts to VPN login endpoints and correlate with threat intelligence feeds to identify emerging threats promptly. Employ rate limiting and anomaly detection on VPN login interfaces to prevent brute force or automated exploitation attempts. Finally, conduct regular security assessments and penetration testing focused on VPN infrastructure to identify and remediate weaknesses proactively.

Indicators of compromise

IP addresses 9

2620:96:e000::126- i Censys - HTTP User-Agent Scanner
78.185.225.166ET INFO Unsupported/Fake Windows NT Version 5.0
80.88.171.245ET INFO Unsupported/Fake Windows NT Version 5.0
2001:470:2cc:1::21fET EXPLOIT Fortigate VPN - Repeated GET Requests to /remote/logincheck (CVE-2023-27997)
116.203.88.140ET INFO Unsupported/Fake Windows NT Version 5.0
2001:ee0:42cb:2ab8:6cd8:df15:1d1e:e36dET INFO Unsupported/Fake Windows NT Version 5.0
45.179.2.163ET INFO Unsupported/Fake Windows NT Version 5.0
2001:470:1:c84::16ET EXPLOIT Fortigate VPN - Repeated GET Requests to /remote/logincheck (CVE-2023-27997)
190.175.93.188ET INFO Unsupported/Fake Windows NT Version 5.0

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Description

AI analysisMachine-generated, updated 23 Jan 2026, 05:35 UTC

Indicators of compromise

IP addresses 9

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