The KRVTZ IDS alerts dated 2026-01-21 detail a series of network reconnaissance activities detected by intrusion detection systems, primarily targeting Fortigate VPN devices and other network services. A key technical indicator is repeated GET requests to the /remote/logincheck endpoint on Fortigate VPN appliances, associated with CVE-2023-27997. This vulnerability allows unauthenticated attackers to bypass authentication mechanisms and potentially execute arbitrary commands on vulnerable devices, posing a significant security risk. The alerts also include suspicious HTTP user-agent strings that mimic legitimate browsers but contain anomalous versioning, indicative of automated scanning tools or reconnaissance frameworks. Furthermore, scanning for exposed SFTP/FTP credentials via publicly accessible sftp-config.json files was observed, which could lead to credential compromise and unauthorized access. These activities are categorized as reconnaissance and information-gathering, representing preliminary steps in the cyber kill chain. No patches or direct mitigations are referenced in the alert, and no known exploits in the wild have been reported, suggesting these are early-stage observations. The data originates from the CIRCL OSINT feed, emphasizing open-source intelligence collection. The overall severity is low in the alert but considering the vulnerability involved, the threat warrants attention from organizations using Fortigate VPN appliances. The alerts do not specify targeted countries or affected versions, but the technical indicators provide actionable intelligence for network defenders to monitor and respond accordingly.

For European organizations, the primary impact centers on the potential exploitation of Fortigate VPN devices vulnerable to CVE-2023-27997. Successful exploitation could allow attackers to bypass authentication, execute arbitrary commands, and gain unauthorized access to internal networks, compromising confidentiality, integrity, and availability of critical systems. Given Fortigate's widespread deployment across Europe for secure remote access, this vulnerability presents a significant risk if unpatched. The reconnaissance activities also indicate active attacker efforts to map networks and identify exposed credentials, which could facilitate lateral movement, privilege escalation, or data exfiltration in subsequent attack phases. Although no active exploitation is currently reported, the scanning activity increases the likelihood of targeted attacks. Organizations operating SFTP/FTP services with misconfigured or exposed credential files risk credential theft and unauthorized access. Sectors such as critical infrastructure, finance, government, and large enterprises are particularly vulnerable due to their reliance on Fortigate VPN and the strategic value of their data. Failure to address these reconnaissance indicators could lead to more severe incidents, including ransomware or espionage campaigns.

1. Immediately verify and apply all available security patches for Fortigate VPN appliances, especially those addressing CVE-2023-27997. 2. Implement multi-factor authentication (MFA) on all VPN access points to mitigate risks from credential compromise or authentication bypass. 3. Continuously monitor VPN logs for repeated or anomalous GET requests to /remote/logincheck and other suspicious endpoints indicative of scanning or exploitation attempts. 4. Conduct thorough audits of SFTP/FTP servers to ensure sensitive configuration files like sftp-config.json are not publicly accessible and do not contain exposed credentials. 5. Deploy and tune network intrusion detection and prevention systems to detect reconnaissance patterns and suspicious user-agent strings as identified in the alerts. 6. Restrict VPN and management interface access to trusted IP ranges or VPN gateways to reduce exposure to internet-wide scanning. 7. Educate security teams to recognize reconnaissance activity as a precursor to attacks and establish incident response procedures for such detections. 8. Leverage threat intelligence feeds, such as CIRCL OSINT, to stay updated on emerging scanning IPs and tactics for proactive blocking or investigation. 9. Harden VPN configurations by disabling legacy protocols and enforcing strong encryption and authentication mechanisms. 10. Regularly perform penetration testing and vulnerability assessments to identify and remediate potential exposure points before attackers can exploit them.