THE THREAT:
On June 29th, 2020, Palo Alto announced an authentication-bypass vulnerability (CVE-2020-2021) affecting multiple PAN-OS versions used in VPN appliances and Firewalls [1]. The vulnerability affects Security Assertion Markup Language (SAML) authentication. If exploited, threat actors with unauthenticated network access may gain access to protected resources. Additionally, attackers with access to PAN-OS or Panorama web interfaces could perform administrative actions. The vulnerability has not been identified as being exploited in the wild at this time but attacks are expected in the immediate future, given the simplicity of exploitation [2].
What we’re doing about it
- MVS (formerly esRECON) has a plugin to identify vulnerable PAN-OS versions.
- esLOG monitors for configuration changes in Palo Alto Firewalls. Please speak with your eSentire representative to confirm or enable configuration alerting
- esLOG tracks and alerts unusual sign-in activity for VPN services such as Global Protect. Please speak with your eSentire representative to confirm or enable the ingestion of Palo Alto logs into esLOG
- eSentire security teams continue to track this topic for additional details and detection opportunities
What you should do about it
- Immediately test and apply recommended security updates
- If upgrades cannot be applied, review and apply workarounds from Palo Alto Networks
Detailed instructions for upgrades and workarounds can be found here.
Additional information
Palo Alto devices are impacted if all of the following configurations are in place:
- Running an impacted version of PAN-OS (see below)
- SAML authentication is enabled
- “Validate Identity Provider Certificate” SAML configuration option is disabled.
Impacted PAN-OS versions (Source: Palo Alto Networks):
Vulnerable configurations of Security Assertion Markup Language (SAML) authentication on impacted PAN-OS devices could allow unauthenticated, network-based attacker to access protected resources.
In their advisory, Palo Alto Networks identified the following resources which can be protected by SAML:
- GlobalProtect Gateway
- GlobalProtect Portal
- GlobalProtect Clientless VPN
- Authentication and Captive Portal
- PAN-OS next-generation firewalls (PA-Series, VM-Series) and Panorama web interfaces
- Prisma Access systems
For instructions on identifying vulnerable SAML configurations in PAN devices, see Palo Alto Networks’ advisory and associated knowledge base articles. Customers are encouraged to apply upgrades or workarounds as soon as possible.
References:
[1] https://security.paloaltonetworks.com/CVE-2020-2021
[2] https://twitter.com/CNMF_CyberAlert/status/1277674547542659074