Automated Credential Attacks Storm Cisco & Palo Alto Networks VPNs
Executive Summary
In December 2025, automated credential attacks targeted enterprise VPN gateways from Cisco and Palo Alto Networks. Threat monitoring platforms such as GreyNoise observed a surge of password spraying attempts, with 1.7 million login probes against Palo Alto GlobalProtect portals within 16 hours, and coordinated activity later targeting Cisco SSL VPNs. The attacks originated from over 10,000 unique IPs, predominantly routed through the 3xK GmbH cloud provider in Germany. Attackers employed scripted credential stuffing—leveraging common username and password combinations—to probe for weak authentication endpoints, with no evidence of software vulnerabilities being exploited.
This campaign highlights the ongoing evolution and scale of credential-based attacks targeting critical remote access infrastructure. As password spraying and automated reconnaissance increase, robust authentication and monitoring remain pivotal to defending against perimeter breaches, especially as threat actors exploit enterprise weaknesses during periods of heightened cyber activity.
Why This Matters Now
Enterprises are experiencing a surge in large-scale, automated password attacks targeting VPN infrastructures. Weak credentials and insufficient authentication measures can enable attackers to gain footholds in sensitive environments, making immediate action to bolster identity controls and monitor authentication logs critical to preventing compromise.
Attack Path Analysis
The attack began with large-scale, automated password spraying against exposed Cisco and Palo Alto VPN gateways to identify weak credentials. Upon any successful authentication, the attackers could have escalated privileges by leveraging valid VPN access to internal systems. With access established, lateral movement between internal resources could occur, though no explicit evidence was provided. Attackers could then establish persistent command and control channels via the compromised VPN. Sensitive data could be exfiltrated through encrypted tunnels, and attackers may pursue business disruption or further exploitation as impact. While only the credential attack was observed, subsequent stages are inferred based on common patterns following initial VPN compromise.
Kill Chain Progression
Initial Compromise
Description
Attackers performed automated password spraying against exposed VPN gateways to discover valid credentials using common username-password pairs.
Related CVEs
CVE-2025-20393
CVSS 9.8An improper input validation vulnerability in Cisco AsyncOS Software allows unauthenticated, remote attackers to execute arbitrary code on affected devices.
Affected Products:
Cisco AsyncOS – Affected versions as per vendor advisory
Exploit Status:
exploited in the wildCVE-2025-0114
CVSS 8.2A Denial of Service (DoS) vulnerability in the GlobalProtect feature of Palo Alto Networks PAN-OS software enables an unauthenticated attacker to render the service unavailable by sending a large number of specially crafted packets over a period of time.
Affected Products:
Palo Alto Networks PAN-OS – Affected versions as per vendor advisory
Exploit Status:
active scanning observed
MITRE ATT&CK® Techniques
Brute Force: Password Spraying
Valid Accounts
Gather Victim Identity Information
External Remote Services
Exploit Public-Facing Application
Network Service Scanning
Exploitation for Credential Access
Potential Compliance Exposure
Mapping incident impact across multiple compliance frameworks.
PCI DSS 4.0 – Multi-Factor Authentication for Remote Network Access
Control ID: 8.3.6
NYDFS 23 NYCRR 500 – Multi-Factor Authentication
Control ID: 500.12
DORA (Digital Operational Resilience Act) – ICT Risk Management Framework
Control ID: Art 9
CISA Zero Trust Maturity Model (ZTMM) 2.0 – Centralized Identity and Strong Authentication
Control ID: Identity Pillar
NIS2 Directive – Policies on Access Control and Authentication
Control ID: Article 21(2)(d)
Sector Implications
Industry-specific impact of the vulnerabilities, including operational, regulatory, and cloud security risks.
Financial Services
Password spraying attacks on VPN gateways threaten financial institutions' remote access security, requiring enhanced MFA and Zero Trust segmentation to protect sensitive financial data and comply with regulatory requirements.
Health Care / Life Sciences
Healthcare organizations face critical HIPAA compliance risks from credential attacks on VPN infrastructure, necessitating encrypted traffic protection and threat detection capabilities to secure patient data access points.
Government Administration
Government agencies are prime targets for automated credential probing attacks on VPN gateways, requiring robust egress security policies and anomaly detection to prevent unauthorized access to classified systems.
Information Technology/IT
IT sector organizations managing enterprise VPN infrastructure face direct exposure to large-scale password spraying campaigns, demanding immediate implementation of multicloud visibility and threat response capabilities.
Sources
- New password spraying attacks target Cisco, PAN VPN gatewayshttps://www.bleepingcomputer.com/news/security/new-password-spraying-attacks-target-cisco-pan-vpn-gateways/Verified
- Cisco Security Advisory: Cisco AsyncOS Software Improper Input Validation Vulnerabilityhttps://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sma-attack-N9bf4Verified
- Palo Alto Networks Security Advisory: CVE-2025-0114https://security.paloaltonetworks.com/CVE-2025-0114Verified
Frequently Asked Questions
Cloud Native Security Fabric Mitigations and ControlsCNSF
Zero Trust controls such as segmentation, policy enforcement, and continuous anomaly detection would have limited VPN exposure, blocked unauthorized access, detected credential abuse, and contained potential lateral movement. CNSF-aligned capabilities ensure that only authorized users and devices access sensitive resources, even if perimeter authentication is targeted.
Control: Zero Trust Segmentation
Mitigation: Non-essential VPN portal access could be segmented or restricted, greatly reducing the attack surface.
Control: Multicloud Visibility & Control
Mitigation: Real-time monitoring and policy enforcement detect abnormal session access and privilege misuse.
Control: East-West Traffic Security
Mitigation: Lateral movement between workloads and regions is blocked or tightly controlled.
Control: Threat Detection & Anomaly Response
Mitigation: Unknown or covert C2 traffic patterns are detected and can be blocked.
Control: Egress Security & Policy Enforcement
Mitigation: Unauthorized data exfiltration is detected and denied at the network boundary.
Continuous, inline policy enforcement and network visibility support rapid detection and containment of malicious activities.
Impact at a Glance
Affected Business Functions
- Remote Access
- Network Security
Estimated downtime: 3 days
Estimated loss: $500,000
Potential exposure of sensitive corporate data due to unauthorized access through compromised VPN gateways.
Recommended Actions
Key Takeaways & Next Steps
- • Restrict VPN gateway exposure with identity-driven, least privilege segmentation and strong authentication enforcement.
- • Continuously monitor and baseline access patterns to rapidly detect abnormal authentication or credential abuse.
- • Apply microsegmentation to contain compromised sessions and prevent lateral movement within cloud and hybrid networks.
- • Enforce granular egress policies with real-time inspection to block unauthorized data exfiltration and command channels.
- • Deploy distributed, automated threat detection and response to accelerate identification and remediation of suspicious behaviors.
