CVE-2018-12268 in acccheck
Summary
by MITRE
acccheck.pl in acccheck 0.2.1 allows Command Injection via shell metacharacters in a username or password file, as demonstrated by injection into an smbclient command line.
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Analysis
by VulDB Data Team • 02/19/2020
The vulnerability identified as CVE-2018-12268 represents a critical command injection flaw in the acccheck.pl script version 0.2.1, which is part of the acccheck security toolset designed for network authentication testing. This vulnerability specifically targets the handling of user credentials within the tool's authentication checking functionality, where the script fails to properly sanitize input data before incorporating it into system commands. The flaw exists in how the script processes username and password files, creating an avenue for malicious actors to execute arbitrary commands on the system where acccheck is running.
The technical implementation of this vulnerability stems from improper input validation and sanitization within the acccheck.pl script. When the tool processes authentication credentials from user-provided files, it directly incorporates these values into smbclient command execution without adequate escaping or filtering of shell metacharacters. This design flaw allows attackers to inject malicious command sequences that get executed within the context of the acccheck process, potentially with elevated privileges depending on how the tool is deployed. The vulnerability specifically affects the smbclient command line construction where user-supplied data is concatenated without proper shell escaping mechanisms.
The operational impact of CVE-2018-12268 extends beyond simple command execution, as it can enable full system compromise when acccheck is run with elevated privileges. Attackers can leverage this vulnerability to execute arbitrary commands on the target system, potentially gaining access to sensitive data, establishing persistence mechanisms, or escalating privileges within the network environment. The vulnerability is particularly concerning because it operates at the command-line level where acccheck is commonly used for security auditing, making it a prime target for attackers seeking to exploit network authentication testing tools. This flaw essentially transforms a legitimate security tool into a potential attack vector, undermining the security posture of organizations relying on such tools for vulnerability assessment.
Mitigation strategies for this vulnerability require immediate remediation through input validation and sanitization measures. The most effective approach involves implementing proper shell escaping or command parameterization techniques to prevent metacharacter interpretation during command construction. Organizations should also consider updating to patched versions of acccheck where available, as the vulnerability represents a known flaw that has been addressed in subsequent releases. Additionally, security teams should implement principle of least privilege for acccheck execution, ensuring the tool runs with minimal required permissions and avoid running with elevated privileges during authentication testing. The vulnerability aligns with CWE-78, which specifically addresses improper neutralization of special elements used in OS commands, and can be categorized under ATT&CK technique T1059 for command and scripting interpreter, highlighting the operational security implications of command injection vulnerabilities in security tooling.