CVE-2018-10859 in git-annex
Summary
by MITRE
git-annex is vulnerable to an Information Exposure when decrypting files. A malicious server for a special remote could trick git-annex into decrypting a file that was encrypted to the user's gpg key. This attack could be used to expose encrypted data that was never stored in git-annex
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Analysis
by VulDB Data Team • 04/09/2023
The vulnerability identified as CVE-2018-10859 affects git-annex, a powerful tool for managing large files with git while keeping them encrypted. This information exposure flaw occurs during the decryption process when git-annex interacts with malicious special remotes. The vulnerability stems from insufficient validation of encryption parameters and trust relationships between the client and remote servers. When a user attempts to decrypt files stored in git-annex, the system may be tricked into decrypting content that was originally encrypted to the user's GPG key but was never actually stored within the git-annex repository itself. This represents a significant security risk because it allows attackers to potentially access encrypted data that should have remained protected.
The technical implementation of this vulnerability involves the improper handling of encryption metadata and key management during file decryption operations. Git-annex relies on GPG encryption for securing files, but the flaw allows malicious servers to manipulate the decryption process by presenting forged encryption parameters or misleading information about the original encryption context. This issue is particularly dangerous because it operates at the boundary between encryption and decryption, where trust assumptions are critical. The vulnerability can be exploited through specially crafted special remote implementations that manipulate the expected encryption keys or contexts. According to CWE standards, this corresponds to CWE-200 Information Exposure, which occurs when sensitive information is unintentionally made available to unauthorized actors. The attack vector aligns with ATT&CK technique T1552.001 for Unsecured Credentials and T1074.001 for Data Staged for Exfiltration.
The operational impact of CVE-2018-10859 extends beyond simple data leakage, as it undermines the fundamental security assumptions of git-annex's encryption model. An attacker who successfully exploits this vulnerability could gain access to sensitive information that was never intended to be exposed through the normal git-annex workflow. This includes potentially accessing files that were encrypted using the user's private key but were never actually stored in the repository, representing a critical failure in access control and data integrity. The vulnerability particularly affects users who rely on git-annex for secure file management and who may unknowingly interact with malicious special remotes. The implications are severe because it allows for the compromise of data that should remain encrypted and protected, even if it was never stored in the repository itself, effectively bypassing the intended security boundaries.
Mitigation strategies for CVE-2018-10859 require a multi-layered approach focusing on both immediate remediation and long-term security hardening. Users should immediately update to git-annex versions that address this vulnerability, as the fix typically involves strengthening the validation of encryption parameters and implementing stricter trust verification mechanisms. Organizations should implement strict access controls for special remotes and carefully vet any remote servers before establishing connections. The security model should be enhanced to validate encryption contexts more rigorously during decryption operations, ensuring that files are only decrypted when the system can verify the original encryption parameters match the expected context. Additionally, implementing network monitoring and anomaly detection for unusual decryption patterns can help identify potential exploitation attempts. Regular security audits of git-annex configurations and special remote implementations are essential to prevent similar vulnerabilities from emerging in the future, while also ensuring that the established trust relationships between users and remote servers remain intact and secure.