CVE-2015-7545 in Git
Summary
by MITRE
The (1) git-remote-ext and (2) unspecified other remote helper programs in Git before 2.3.10, 2.4.x before 2.4.10, 2.5.x before 2.5.4, and 2.6.x before 2.6.1 do not properly restrict the allowed protocols, which might allow remote attackers to execute arbitrary code via a URL in a (a) .gitmodules file or (b) unknown other sources in a submodule.
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Analysis
by VulDB Data Team • 07/24/2022
The vulnerability identified as CVE-2015-7545 represents a critical remote code execution flaw affecting Git versions prior to specific patches. This vulnerability specifically impacts git-remote-ext and other remote helper programs within the Git ecosystem, creating a pathway for malicious actors to execute arbitrary code on systems that process untrusted Git submodule configurations. The flaw stems from insufficient protocol validation mechanisms that fail to properly restrict the allowed protocols, enabling attackers to craft malicious URLs that bypass security controls. This vulnerability operates at the intersection of software supply chain security and remote execution risks, particularly affecting developers who regularly work with Git submodules and external repositories.
The technical implementation of this vulnerability exploits the trust model inherent in Git's submodule handling mechanisms. When Git processes .gitmodules files or other submodule configurations, it attempts to validate and execute remote helper commands based on URL protocols specified within these configuration files. The flaw occurs because Git does not adequately validate the protocol schemes used in these URLs, allowing attackers to specify protocols that should be restricted or prohibited. This misconfiguration enables attackers to craft URLs that, when processed by git-remote-ext or similar helper programs, can trigger execution of arbitrary commands on the target system. The vulnerability specifically affects versions before 2.3.10, 2.4.x before 2.4.10, 2.5.x before 2.5.4, and 2.6.x before 2.6.1, indicating a widespread impact across multiple release branches of the Git version control system.
The operational impact of CVE-2015-7545 extends far beyond individual system compromises, creating potential for widespread supply chain attacks and code injection scenarios. Attackers can exploit this vulnerability by manipulating submodule configurations in repositories they control or compromise, leading to remote code execution on systems that subsequently process these configurations. The attack vector typically involves crafting malicious .gitmodules files that contain specially crafted URLs with unauthorized protocols, which when processed by vulnerable Git installations can result in arbitrary command execution. This vulnerability particularly affects development environments where Git submodules are extensively used, as well as automated build systems and continuous integration pipelines that rely on Git operations. The implications are significant for organizations that maintain large codebases with multiple submodules, as a single compromised submodule can potentially compromise entire development environments.
Mitigation strategies for CVE-2015-7545 primarily focus on upgrading to patched versions of Git where the protocol validation has been strengthened. Organizations should immediately update their Git installations to versions 2.3.10, 2.4.10, 2.5.4, or 2.6.1 respectively, depending on their current version. Additionally, administrators should implement strict validation of submodule configurations, particularly those sourced from untrusted repositories, and consider implementing network-level restrictions that prevent access to potentially malicious remote protocols. The vulnerability aligns with CWE-20, which describes improper input validation, and maps to ATT&CK technique T1133, which involves external remote services. Organizations should also consider implementing automated scanning tools that can detect and flag potentially malicious submodule configurations, as well as establishing secure development practices that minimize the exposure to untrusted submodule sources. Regular security audits of Git configurations and submodule usage patterns can help identify and remediate similar vulnerabilities before they can be exploited.