CVE-2017-5207 in Firejail
Summary
by MITRE
Firejail before 0.9.44.4, when running a bandwidth command, allows local users to gain root privileges via the --shell argument.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 11/15/2022
The vulnerability identified as CVE-2017-5207 resides within Firejail, a security sandboxing tool designed to restrict the capabilities of applications and prevent privilege escalation attacks. This particular flaw affects versions prior to 0.9.44.4 and represents a critical security weakness that allows local attackers to escalate their privileges from standard user level to root access. The vulnerability specifically manifests when Firejail executes bandwidth management commands, which are commonly used to control network traffic for sandboxed applications. The exploitation occurs through the improper handling of the --shell argument, which creates an opportunity for privilege escalation.
The technical flaw stems from Firejail's insufficient validation and sanitization of command-line arguments when executing bandwidth-related operations. When a user invokes a bandwidth command with the --shell argument, the system fails to properly isolate or restrict the execution environment, allowing malicious input to be interpreted as shell commands. This represents a classic command injection vulnerability that can be leveraged to execute arbitrary code with elevated privileges. The vulnerability operates at the operating system level where Firejail, despite its sandboxing capabilities, fails to properly handle user-supplied arguments that could be interpreted as shell commands rather than legitimate configuration parameters. This flaw aligns with CWE-78, which describes improper neutralization of special elements used in shell commands, and demonstrates how sandboxing tools can still contain critical implementation gaps.
The operational impact of this vulnerability is severe for any system running affected versions of Firejail, particularly in multi-user environments where local users might attempt to exploit this weakness. Attackers can leverage this privilege escalation vector to gain full root access to the system, potentially leading to complete compromise of the affected machine. The vulnerability is particularly dangerous because it requires minimal privileges to exploit, as local users already have access to the system. Once root access is obtained, attackers can modify system files, install backdoors, steal sensitive data, or use the compromised system as a launch point for further attacks. This vulnerability directly violates the principle of least privilege and undermines the fundamental security assumptions of the Firejail sandboxing mechanism, which is designed to prevent exactly this type of privilege escalation.
Mitigation strategies for CVE-2017-5207 focus primarily on upgrading to Firejail version 0.9.44.4 or later, which contains the necessary patches to address the improper argument handling. System administrators should also implement additional security measures such as restricting user access to Firejail commands, monitoring for unusual bandwidth command usage patterns, and ensuring proper privilege separation in the system configuration. The fix implemented in the patched version addresses the core issue by properly sanitizing and validating all command-line arguments, particularly those related to shell execution. Organizations should also consider implementing the principle of defense in depth by combining the Firejail upgrade with other security controls including regular system auditing, intrusion detection systems, and proper access control policies. This vulnerability demonstrates the importance of thorough input validation in security tools and highlights how even well-established sandboxing solutions can contain critical flaws that require ongoing security assessment and patch management. The ATT&CK framework categorizes this vulnerability under privilege escalation techniques, specifically leveraging weaknesses in application security controls to gain elevated system privileges.