CVE-2020-2040 in PAN-OS
Summary
by MITRE
A buffer overflow vulnerability in PAN-OS allows an unauthenticated attacker to disrupt system processes and potentially execute arbitrary code with root privileges by sending a malicious request to the Captive Portal or Multi-Factor Authentication interface. This issue impacts: All versions of PAN-OS 8.0; PAN-OS 8.1 versions earlier than PAN-OS 8.1.15; PAN-OS 9.0 versions earlier than PAN-OS 9.0.9; PAN-OS 9.1 versions earlier than PAN-OS 9.1.3.
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Analysis
by VulDB Data Team • 09/09/2020
The buffer overflow vulnerability identified as CVE-2020-2040 represents a critical security flaw within Palo Alto Networks PAN-OS operating systems that affects multiple version lines including 8.0, 8.1, 9.0, and 9.1. This vulnerability specifically targets the Captive Portal and Multi-Factor Authentication interfaces, creating a pathway for unauthenticated attackers to compromise system integrity. The flaw stems from inadequate input validation mechanisms that fail to properly handle oversized data payloads when processing requests through these authentication interfaces. According to CWE-121, this vulnerability manifests as a classic stack-based buffer overflow condition where malicious input exceeds the allocated buffer space, potentially leading to memory corruption and arbitrary code execution. The attack vector is particularly concerning as it requires no authentication credentials, making it accessible to any external party capable of sending crafted requests to affected systems.
The technical implementation of this vulnerability involves the exploitation of insufficient bounds checking within the PAN-OS authentication processing modules. When a malicious request is received through the Captive Portal or Multi-Factor Authentication interface, the system fails to validate the length of incoming data before copying it into fixed-size buffers. This allows an attacker to overflow the buffer and overwrite adjacent memory locations, potentially corrupting program execution flow and control structures. The impact extends beyond simple disruption as the vulnerability can be leveraged to execute arbitrary code with root privileges, effectively granting complete system compromise. The specific memory corruption patterns observed in this vulnerability align with ATT&CK technique T1059.007 for command and scripting interpreter, where attackers can leverage the overflow to inject and execute malicious payloads. The affected PAN-OS versions represent a significant portion of the deployed base, with the vulnerability present in all 8.0 releases and specific earlier releases of 8.1, 9.0, and 9.1 versions.
The operational impact of CVE-2020-2040 is severe and multifaceted, potentially enabling complete system takeover without any authentication requirements. An attacker who successfully exploits this vulnerability can gain root-level access to the affected PAN-OS device, allowing for persistent backdoor installation, data exfiltration, and further network infiltration. The disruption potential includes service degradation, denial of service conditions, and complete system compromise that could affect network security policies and traffic filtering capabilities. Organizations running affected PAN-OS versions face immediate risk of unauthorized access to their network infrastructure, potentially exposing sensitive data and creating attack vectors for lateral movement within their network environments. The vulnerability's presence across multiple major release lines indicates a widespread exposure that requires urgent remediation across affected deployments.
Mitigation strategies for CVE-2020-2040 should prioritize immediate patch application to the latest available PAN-OS versions that contain the necessary security fixes. Organizations must upgrade to PAN-OS 8.1.15, 9.0.9, or 9.1.3 respectively, depending on their current version, to eliminate the buffer overflow conditions. Network segmentation and access control measures should be implemented to limit exposure of affected authentication interfaces to trusted networks only, reducing the attack surface. Monitoring systems should be configured to detect unusual traffic patterns or malformed requests to the Captive Portal and Multi-Factor Authentication interfaces, providing early warning of potential exploitation attempts. Additionally, implementing web application firewalls and intrusion detection systems can help identify and block malicious requests before they reach vulnerable components. The remediation process should include thorough testing of patched systems to ensure that security updates do not introduce compatibility issues with existing network configurations and services.