What happened
A large, coordinated credential‑based VPN attack recently focused on breaching remote access gateways, specifically Palo Alto Networks GlobalProtect and Cisco SSL VPN services. Rather than exploiting software flaws, the attackers used automated login scripts to attempt to guess or reuse credentials over a concentrated two‑day period in mid‑December, generating millions of login attempts and thousands of unique source IPs.
Who is affected
Enterprises using Palo Alto Networks GlobalProtect and Cisco SSL VPN infrastructure for remote access are at risk from these brute‑force style credential attacks. Although there’s no evidence the vendors’ platforms were compromised or vulnerable, the sheer volume of authentication attempts highlights exposure of weak or reused account credentials across many networks.
Why CISOs should care
Credential‑based attacks are a common initial access method that can lead to deeper network infiltration if successful. VPN gateways are often exposed externally and serve as critical entry points into internal systems. Elevated brute‑force activity underscores the importance of strong authentication controls and monitoring, as successful credential compromise can enable lateral movement and deeper intrusion.
3 practical actions:
- Enforce strong authentication: Require unique, complex passwords and implement multi‑factor authentication (MFA) on all VPN and remote access endpoints.
- Monitor authentication patterns: Configure logging and alerting for abnormal login volumes and sources to rapidly detect and respond to credential‑based probing.
- Harden exposed endpoints: Apply rate limiting, IP blocklists for known malicious sources, and regular access reviews to reduce the effectiveness of automated brute‑force attempts.