CVE-2016-7032 in sudo
Summary
by MITRE
sudo_noexec.so in Sudo before 1.8.15 on Linux might allow local users to bypass intended noexec command restrictions via an application that calls the (1) system or (2) popen function.
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Analysis
by VulDB Data Team • 10/18/2019
The vulnerability identified as CVE-2016-7032 represents a critical security flaw in the sudo command execution mechanism on Linux systems, specifically affecting versions prior to 1.8.15. This issue resides within the sudo_noexec.so plugin component that is designed to enforce noexec restrictions on commands executed through sudo. The vulnerability stems from the improper handling of command execution when applications utilize system or popen functions, which can potentially circumvent the intended security controls that prevent execution of certain commands. The flaw allows local attackers to escalate privileges by exploiting the way sudo processes these specific function calls, effectively bypassing the security mechanisms meant to restrict command execution. This represents a significant concern for system administrators who rely on sudo's noexec functionality to maintain security boundaries and prevent unauthorized command execution.
The technical implementation of this vulnerability occurs at the level where sudo processes command execution through the sudo_noexec.so plugin. When applications make calls to system or popen functions, the sudo implementation fails to properly validate or restrict these calls within the context of noexec restrictions. This creates a pathway where commands that should be blocked or restricted can still be executed through these alternative function calls. The vulnerability specifically manifests when sudo encounters these particular API calls and does not properly enforce the noexec policies that would normally prevent execution of commands in restricted contexts. This flaw operates at the intersection of privilege management and command execution, where the security boundary established by noexec restrictions becomes ineffective due to the improper handling of these specific system calls.
The operational impact of CVE-2016-7032 is substantial for Linux systems that rely on sudo's noexec functionality for security control. Local users who can execute commands through sudo with elevated privileges can exploit this vulnerability to bypass intended restrictions and execute commands that should be blocked. This could potentially allow attackers to escalate privileges beyond what was originally intended, leading to unauthorized access to system resources and potential complete system compromise. The vulnerability undermines the fundamental security model that sudo implements, where users are granted specific privileges but should be restricted from executing certain commands. This issue particularly affects systems where sudo is configured with noexec restrictions to prevent execution of shell commands or specific binaries, making it a critical concern for enterprise environments and security-conscious deployments.
The mitigation strategy for CVE-2016-7032 involves immediate patching of sudo to version 1.8.15 or later, which contains the necessary fixes to properly enforce noexec restrictions regardless of how commands are executed through system or popen functions. System administrators should also review sudo configuration files to ensure that noexec restrictions are properly implemented and that unnecessary privileges are not granted to users. Additionally, monitoring for unauthorized sudo usage and implementing proper access controls can help detect potential exploitation attempts. This vulnerability aligns with CWE-284 Access Control issues and represents a privilege escalation vector that could be mapped to ATT&CK technique T1068, which covers privilege escalation through the exploitation of system vulnerabilities. Organizations should also consider implementing additional security controls such as privilege separation, command whitelisting, and comprehensive audit logging to prevent exploitation of similar vulnerabilities in the future.