CVE-2017-14176 in Bazaar
Summary
by MITRE
Bazaar through 2.7.0, when Subprocess SSH is used, allows remote attackers to execute arbitrary commands via a bzr+ssh URL with an initial dash character in the hostname, a related issue to CVE-2017-9800, CVE-2017-12836, CVE-2017-12976, CVE-2017-16228, CVE-2017-1000116, and CVE-2017-1000117.
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Analysis
by VulDB Data Team • 01/16/2023
The vulnerability identified as CVE-2017-14176 affects the Bazaar version control system through version 2.7.0, specifically when utilizing Subprocess SSH functionality. This security flaw represents a command injection vulnerability that arises from improper handling of SSH URLs containing maliciously crafted hostnames. The issue manifests when a bzr+ssh URL begins with a dash character in the hostname portion, creating a dangerous condition where attacker-controlled input can be interpreted as command-line arguments rather than simple hostname data. This vulnerability operates under the broader category of command injection flaws, which are categorized under CWE-77 in the Common Weakness Enumeration framework, specifically targeting improper neutralization of special elements used in command execution contexts.
The technical mechanism of exploitation involves the Bazaar client's interaction with SSH subprocesses where the hostname parameter is directly passed to underlying system commands without proper sanitization or argument escaping. When a malicious hostname begins with a dash character, it is interpreted by the SSH command as the beginning of a command-line option rather than a literal hostname string. This misinterpretation allows attackers to inject arbitrary command-line arguments that get executed with the privileges of the user running the Bazaar process. The vulnerability is particularly concerning because it leverages existing SSH infrastructure and can be exploited through standard version control operations, making it difficult to detect and prevent through conventional security measures.
The operational impact of this vulnerability extends beyond simple command execution, as it can potentially lead to complete system compromise when the Bazaar process runs with elevated privileges. Attackers could leverage this flaw to execute arbitrary code on systems where Bazaar is installed, potentially gaining access to source code repositories, system files, or even establishing persistent access through backdoor creation. The vulnerability affects environments where Bazaar is used for code management and where SSH connections are configured for remote repository access, making it particularly dangerous in development environments and continuous integration systems where automated processes might be running with elevated permissions. This type of vulnerability aligns with ATT&CK technique T1059.001 for command and scripting interpreter, specifically targeting the execution of system commands through legitimate system utilities.
Mitigation strategies for CVE-2017-14176 should focus on both immediate patching and operational controls. The most effective solution is updating to Bazaar version 2.8.0 or later, which includes proper input sanitization for SSH URL parameters. Organizations should also implement strict input validation for repository URLs, particularly when they are dynamically generated or sourced from untrusted inputs. Network-level controls such as firewall rules that restrict direct SSH access to repository servers can help reduce the attack surface, while monitoring systems should be configured to detect unusual command execution patterns. Additionally, implementing principle of least privilege for Bazaar processes, ensuring they run with minimal required permissions, can limit the potential damage from successful exploitation. The vulnerability demonstrates the critical importance of proper input handling in system utilities and underscores the need for robust security testing of command-line argument processing in version control systems.