CVE-2020-2033 in GlobalProtect App
Summary
by MITRE
When the pre-logon feature is enabled, a missing certification validation in Palo Alto Networks GlobalProtect app can disclose the pre-logon authentication cookie to a man-in-the-middle attacker on the same local area network segment with the ability to manipulate ARP or to conduct ARP spoofing attacks. This allows the attacker to access the GlobalProtect Server as allowed by configured Security rules for the 'pre-login' user. This access may be limited compared to the network access of regular users. This issue affects: GlobalProtect app 5.0 versions earlier than GlobalProtect app 5.0.10 when the prelogon feature is enabled; GlobalProtect app 5.1 versions earlier than GlobalProtect app 5.1.4 when the prelogon feature is enabled.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 10/24/2020
The vulnerability identified as CVE-2020-2033 represents a critical security flaw in Palo Alto Networks GlobalProtect client software that specifically impacts pre-logon authentication functionality. This issue manifests when the pre-logon feature is enabled, creating a scenario where authentication cookies are transmitted without proper certificate validation, leaving the system susceptible to man-in-the-middle attacks within the same local network segment. The vulnerability is particularly concerning because it directly compromises the integrity of the authentication process before users have successfully logged into the network, creating a window of opportunity for attackers to exploit.
The technical flaw stems from insufficient certificate validation mechanisms within the GlobalProtect application's pre-logon authentication flow. When pre-logon functionality is active, the system fails to properly validate the certificates presented by the GlobalProtect server, allowing an attacker positioned on the same network segment to intercept and manipulate the authentication cookie. This weakness enables attackers to conduct ARP spoofing attacks or manipulate Address Resolution Protocol tables to position themselves between legitimate communication parties. The vulnerability is classified under CWE-295 which specifically addresses "Improper Certificate Validation" and aligns with ATT&CK technique T1566.001 for "Phishing: Spearphishing Attachment" and T1071.004 for "Application Layer Protocol: DNS" as attackers may leverage this weakness to establish persistent access through compromised authentication tokens.
The operational impact of this vulnerability extends beyond simple credential theft, as it allows attackers to gain access to the GlobalProtect server with permissions granted by configured security rules for pre-login users. While the access may be more limited compared to regular authenticated users, the attacker can still potentially access network resources that are specifically permitted for pre-logon users, creating unauthorized access points within the network infrastructure. This vulnerability particularly affects versions 5.0.x prior to 5.0.10 and 5.1.x prior to 5.1.4 of the GlobalProtect client application, making organizations using these versions highly susceptible to exploitation if they have pre-logon features enabled.
Organizations should implement immediate mitigations including updating to the patched versions of GlobalProtect client software, disabling pre-logon functionality where possible, and implementing network segmentation measures to limit the scope of potential ARP spoofing attacks. Network administrators should also consider deploying ARP monitoring tools to detect suspicious ARP table modifications and implement additional authentication layers beyond the basic GlobalProtect authentication. The vulnerability demonstrates the importance of certificate validation in secure communication protocols and highlights the need for comprehensive security testing of authentication mechanisms before deployment. Organizations should also review their security policies to ensure that pre-logon features are only enabled when absolutely necessary and that appropriate network controls are in place to prevent unauthorized access to network resources during the authentication process.