CVE-2020-11581 in Pulse Connect Secure
Summary
by MITRE
An issue was discovered in Pulse Secure Pulse Connect Secure (PCS) through 2020-04-06. The applet in tncc.jar, executed on macOS, Linux, and Solaris clients when a Host Checker policy is enforced, allows a man-in-the-middle attacker to perform OS command injection attacks (against a client) via shell metacharacters to the doCustomRemediateInstructions method, because Runtime.getRuntime().exec() is used.
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Analysis
by VulDB Data Team • 05/17/2024
This vulnerability exists within Pulse Secure Pulse Connect Secure version 2020-04-06 and earlier, specifically affecting the tncc.jar applet component that operates on macOS, Linux, and Solaris client systems. The flaw manifests when Host Checker policies are enforced, creating a critical security gap that enables remote attackers to execute arbitrary operating system commands on vulnerable client machines. The vulnerability stems from improper input validation within the doCustomRemediateInstructions method where the application directly invokes Runtime.getRuntime().exec() without adequate sanitization of user-supplied parameters. This primitive command execution mechanism creates a pathway for attackers to inject malicious shell metacharacters that are then interpreted and executed by the underlying operating system, effectively allowing full command injection capabilities against the compromised client systems.
The technical exploitation of this vulnerability follows a man-in-the-middle attack pattern where an attacker positioned between the client and the secure gateway can manipulate network traffic to inject malicious command sequences. The attack vector specifically targets the tncc.jar applet which is designed to execute remediation instructions on client systems, but due to the lack of proper input sanitization, any shell metacharacters passed to the doCustomRemediateInstructions method are directly forwarded to the exec() function. This represents a classic command injection vulnerability that aligns with CWE-77 and CWE-88 classifications, where user-controllable data flows directly into command execution contexts without proper validation or escaping mechanisms. The vulnerability is particularly concerning because it operates at the client-side execution level, allowing attackers to execute arbitrary commands with the privileges of the affected user account.
The operational impact of this vulnerability extends beyond simple command execution, as it provides attackers with the capability to perform complete system compromise of affected client machines. Once exploited, an attacker could potentially escalate privileges, establish persistent backdoors, exfiltrate sensitive data, or use the compromised client as a pivot point for further network reconnaissance and lateral movement. The vulnerability affects multiple operating systems including macOS, Linux, and Solaris, creating a broad attack surface that increases the likelihood of successful exploitation across different client environments. From an adversary perspective, this vulnerability aligns with ATT&CK technique T1059.001 for Command and Scripting Interpreter and T1078.004 for Valid Accounts, as it allows for execution of arbitrary commands and can be leveraged for privilege escalation. The attack requires minimal sophistication and can be automated, making it particularly dangerous for enterprise environments where multiple client systems may be simultaneously vulnerable.
Organizations should implement immediate mitigations including updating to the latest Pulse Connect Secure version that addresses this vulnerability, disabling Host Checker policies when possible, and implementing network segmentation to limit the attack surface. The recommended approach involves applying vendor security patches as soon as they become available, while also considering network-based controls such as firewall rules that restrict communication with vulnerable components. Additionally, organizations should conduct thorough inventory assessments to identify all affected client systems and implement monitoring solutions to detect potential exploitation attempts. The vulnerability demonstrates the critical importance of input validation and secure coding practices, particularly when dealing with dynamic command execution in client-side applications. Security teams should also consider implementing endpoint detection and response solutions that can identify suspicious command execution patterns and anomalous behavior that may indicate exploitation attempts.