CVE-2017-5206 in Firejail
Summary
by MITRE
Firejail before 0.9.44.4, when running on a Linux kernel before 4.8, allows context-dependent attackers to bypass a seccomp-based sandbox protection mechanism via the --allow-debuggers argument.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 11/15/2022
The vulnerability identified as CVE-2017-5206 represents a critical sandbox bypass issue within the Firejail security framework that affected versions prior to 0.9.44.4. This flaw specifically manifests when Firejail operates on Linux kernel versions earlier than 4.8, creating a significant security gap that adversaries can exploit to circumvent intended protection mechanisms. The vulnerability stems from the improper handling of seccomp-based sandbox protections when the --allow-debuggers argument is utilized, fundamentally undermining the security posture that users expect from sandboxed environments.
The technical implementation of this vulnerability lies in the interaction between Firejail's sandboxing capabilities and the Linux kernel's seccomp filtering system. When the --allow-debuggers flag is employed, the sandbox mechanism fails to properly restrict system call filtering, allowing malicious actors to execute privileged operations that should otherwise be blocked. This occurs because the seccomp filter configuration becomes insufficiently restrictive when debuggers are permitted, creating an attack surface that bypasses the intended security boundaries. The flaw operates at the kernel level where system call interception mechanisms are compromised, enabling unauthorized access to system resources that should remain isolated within the sandboxed environment.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it fundamentally compromises the integrity of sandboxed applications and processes. Attackers can leverage this bypass to execute arbitrary code within the sandboxed environment, potentially accessing sensitive data, escalating privileges, or using the compromised sandbox as a launch point for further attacks. The vulnerability affects organizations relying on Firejail for containerized applications, virtualized environments, and security isolation, where the expected protection boundaries are rendered ineffective. This issue particularly impacts systems running older kernel versions where the underlying seccomp functionality has not been properly enhanced to address the specific interaction with debugger permissions.
The security implications of CVE-2017-5206 align with CWE-284, which addresses improper access control in software systems, and can be categorized under ATT&CK technique T1197 for Defense Evasion through sandbox evasion. Organizations utilizing Firejail for security isolation must understand that this vulnerability creates a pathway for attackers to bypass critical security controls designed to prevent unauthorized system access. The flaw demonstrates how seemingly benign configuration options can introduce significant security weaknesses when combined with specific kernel versions, highlighting the importance of comprehensive security testing across different system configurations. System administrators and security teams should implement immediate patching strategies to address this vulnerability, as it represents a direct threat to the security assumptions underlying sandboxed execution environments.
The recommended mitigation approach involves upgrading Firejail to version 0.9.44.4 or later, which includes fixes specifically addressing the seccomp filter bypass mechanism. Additionally, organizations should consider implementing kernel version checks to ensure compatibility with Firejail's security features, particularly when deploying systems that rely on older kernel versions. The patch addresses the core issue by strengthening the seccomp filter configuration when the --allow-debuggers argument is specified, ensuring that system call restrictions remain effective regardless of debugger permissions. Security monitoring should also be enhanced to detect unusual system call patterns that might indicate exploitation attempts, while maintaining awareness of the specific kernel version requirements for optimal Firejail functionality.