The KRVTZ IDS alerts dated 2026-01-23 provide intelligence on network reconnaissance activities detected by intrusion detection systems. The alerts include multiple IP addresses identified as scanning or probing network assets. Several IPs are associated with the detection of fake or unsupported Windows NT 5.0 user-agent strings, a common tactic used by automated scanners to fingerprint systems and evade detection. Critically, some IPv6 addresses have been observed making repeated GET requests to the /remote/logincheck endpoint on Fortigate VPN devices, which corresponds to attempts to exploit CVE-2023-27997. This CVE relates to a vulnerability in Fortinet Fortigate VPN appliances that allows unauthenticated attackers to bypass authentication or cause denial of service via crafted HTTP requests. Although no confirmed exploits in the wild or ransomware campaigns are linked to these alerts, the scanning activity indicates ongoing reconnaissance that could be a precursor to exploitation attempts. The alerts are categorized under OSINT and network activity, emphasizing their reconnaissance and information-gathering nature. No patches or mitigation guidance are provided in the alert, and the severity is marked as low, reflecting the current stage of the threat as primarily exploratory rather than actively harmful. The lack of affected versions or CVSS score suggests this is an observational report rather than a direct vulnerability advisory.

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.

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.