Summary (Bottom Line Up Front)
IP address 173.239.240.234 conducted a sustained credential attack campaign against Cisco ASA SSL VPN infrastructure from March 10-14, 2026, generating 2,738 authentication attempts using the credentials "clientes/Winter2026!". This represents a HIGH threat level with 85% confidence due to the targeted nature of VPN exploitation and potential for network-level access if successful. Immediate credential validation and access log review is recommended for organizations operating Cisco ASA SSL VPN services.
Activity Timeline
INITIAL REPORT2026-03-14T17:32:57Z
Source: batch_hunting
IP address 173.239.240.234 conducted a sustained credential attack campaign against Cisco ASA SSL VPN infrastructure from March 10-14, 2026, generating 2,738 authentication attempts using the credentials "clientes/Winter2026!". This represents a HIGH threat level with 85% confidence due to the targeted nature of VPN exploitation and potential for network-level access if successful. Immediate credential validation and access log review is recommended for organizations operating Cisco ASA SSL VPN services.
Technical details
The attacker utilized HTTPS/TLS protocols to target WebVPN endpoints over a 4-day period, concentrating attacks on a single destination port. Primary attack vectors included authentication bypass attempts (T1110.001 - Password Spraying) and credential stuffing operations targeting router default credentials. The campaign generated 180 high-confidence authentication attack events and 180 credential-based attack signatures. The threat actor demonstrated knowledge of Cisco ASA infrastructure and employed systematic credential testing against SSL VPN portals. Attack activity correlates with CVE-2018-0296 exploitation patterns, though zero-day probability remains low at 10%.
IOCs
IP:173.239.240.234
COUNTRY:US
Recommendations
- Immediately verify if credentials "clientes/Winter2026!" exist in your environment and disable/rotate if found
- Review Cisco ASA SSL VPN access logs for successful authentications from 173.239.240.234 between March 10-14, 2026
- Implement rate limiting and account lockout policies on VPN authentication endpoints to prevent brute force attacks
- Apply latest security patches for Cisco ASA devices, particularly addressing CVE-2018-0296 if not already remediated
- Monitor for unusual VPN login patterns and consider implementing multi-factor authentication for all remote access accounts