CVE-2020-1994 in PAN-OS
Summary
by MITRE
A predictable temporary file vulnerability in PAN-OS allows a local authenticated user with shell access to corrupt arbitrary system files affecting the integrity of the system. This issue affects: All versions of PAN-OS 7.1 and 8.0; PAN-OS 8.1 versions earlier than 8.1.13; PAN-OS 9.0 versions earlier than 9.0.7.
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Analysis
by VulDB Data Team • 10/17/2020
The vulnerability identified as CVE-2020-1994 represents a critical predictable temporary file flaw within PAN-OS firewall software that undermines system integrity through a well-known attack vector. This issue stems from improper handling of temporary files during system operations, creating opportunities for privilege escalation and arbitrary file corruption. The vulnerability specifically affects Palo Alto Networks firewalls running various versions of their operating system, making it a widespread concern across multiple release lines.
The technical exploitation of this vulnerability occurs when a local authenticated user with shell access manipulates the predictable naming patterns of temporary files used by PAN-OS processes. This predictable behavior allows attackers to create symbolic links or replace temporary files with malicious content before the system processes them, thereby gaining the ability to corrupt arbitrary system files. The flaw operates at the system level where temporary files are created without sufficient entropy or randomization, enabling attackers to anticipate and control file locations. This vulnerability directly maps to CWE-377, which addresses insecure temporary file creation practices, and aligns with ATT&CK technique T1059.004 for command and scripting interpreter usage in exploitation activities.
The operational impact of CVE-2020-1994 extends beyond simple file corruption, as it provides a pathway for persistent system compromise and potential privilege escalation. An attacker who successfully exploits this vulnerability can manipulate critical system files, potentially leading to complete system compromise or denial of service conditions. The affected PAN-OS versions span multiple major releases, indicating this was a significant flaw that required immediate attention across the product lifecycle. Organizations running these vulnerable versions face increased risk of unauthorized system modifications, data integrity violations, and potential lateral movement within their network infrastructure.
Mitigation strategies for this vulnerability require immediate patching of affected PAN-OS versions to the recommended security updates, specifically versions 8.1.13, 9.0.7, and later releases. Network administrators should implement strict access controls to limit shell access and authentication privileges to only essential personnel. Additionally, monitoring systems should be configured to detect unusual temporary file creation patterns or unexpected file modifications. The vulnerability's exploitation requires local authenticated access, making user access controls and privilege management critical defensive measures. Organizations should also consider implementing network segmentation and endpoint detection capabilities to identify potential exploitation attempts before they can cause significant damage to the firewall infrastructure.