CVE-2020-2016 in PAN-OS
Summary
by MITRE
A race condition due to insecure creation of a file in a temporary directory vulnerability in PAN-OS allows for root privilege escalation from a limited linux user account. This allows an attacker who has escaped the restricted shell as a low privilege administrator, possibly by exploiting another vulnerability, to escalate privileges to become root user.
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Analysis
by VulDB Data Team • 10/17/2020
The vulnerability identified as CVE-2020-2016 represents a critical race condition flaw in Palo Alto Networks PAN-OS operating system that enables unauthorized privilege escalation from limited user accounts to root privileges. This issue stems from insecure file creation practices within temporary directories, creating a window of opportunity for malicious actors to exploit the system's security boundaries. The vulnerability specifically affects PAN-OS versions prior to 9.1.10, 10.0.0, and 10.1.0, making it a significant concern for organizations utilizing affected firewall platforms. The race condition occurs when the system creates temporary files without proper security controls, allowing attackers to manipulate file permissions or contents before the legitimate process can access them.
The technical implementation of this vulnerability involves a race condition scenario where an attacker can exploit the timing window between file creation and file access in temporary directories. When a limited linux user account executes commands within the restricted shell environment, the system's temporary file handling mechanism becomes susceptible to manipulation. The insecure creation process typically involves the use of predictable temporary file names or insufficient permission checks during file creation. This flaw falls under the CWE-367 category of Time-of-Check to Time-of-Use vulnerability, where the system's security checks occur at different points in time, creating exploitable gaps. The vulnerability is particularly dangerous because it allows privilege escalation from a low-privilege administrative user to full root access, bypassing the normal security boundaries of the restricted shell environment.
The operational impact of CVE-2020-2016 extends beyond simple privilege escalation, as it provides attackers with complete system control and access to all network traffic processing capabilities. Once escalated to root privileges, an attacker can modify firewall rules, access all network monitoring data, and potentially establish persistent backdoors within the network infrastructure. The vulnerability is especially concerning in enterprise environments where PAN-OS firewalls serve as critical network security components, as it allows attackers to compromise the entire network security posture. The restricted shell environment that typically limits administrative access becomes ineffective when this vulnerability is exploited, as the escalation bypasses the normal privilege boundaries designed to contain user access. This vulnerability can be leveraged in conjunction with other exploits to create a complete attack chain that ultimately compromises the network infrastructure.
Organizations should implement immediate mitigation strategies including applying the latest PAN-OS patches and updates that address this race condition vulnerability. The vendor has released specific versions 9.1.10, 10.0.0, and 10.1.0 that contain fixes for this issue, and administrators should prioritize deployment of these updates across all affected systems. Additional mitigations include implementing strict temporary file permissions, monitoring for unusual file creation patterns in temporary directories, and enhancing the restricted shell environment with additional security controls. Security teams should also conduct comprehensive vulnerability assessments to identify any potential exploitation attempts and implement network monitoring solutions that can detect suspicious privilege escalation activities. The ATT&CK framework categorizes this vulnerability under privilege escalation techniques, specifically targeting the T1068 technique for local privilege escalation, making it a critical component in network security threat modeling and incident response planning.