CVE-2016-10099 in Borg
Summary
by MITRE
Borg (aka BorgBackup) before 1.0.9 has a flaw in the cryptographic protocol used to authenticate the manifest (list of archives), potentially allowing an attacker to spoof the list of archives.
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Analysis
by VulDB Data Team • 07/13/2020
The vulnerability identified as CVE-2016-10099 affects BorgBackup version 1.0.9 and earlier, representing a critical flaw in the cryptographic authentication mechanism designed to protect the manifest file that contains the list of archives within the backup system. This issue stems from a weakness in how the cryptographic protocol validates the integrity and authenticity of the manifest, which serves as the authoritative reference for all archived data within the BorgBackup environment. The manifest file plays a crucial role in maintaining the backup repository's consistency and ensuring that users can reliably access their archived data. When the authentication mechanism fails, it creates a potential attack vector where malicious actors could manipulate the manifest without detection, leading to a complete breakdown of the backup system's integrity guarantees.
The technical flaw manifests in the cryptographic protocol's implementation where the authentication of the manifest does not properly validate the cryptographic signatures or integrity checks that should prevent unauthorized modifications. This weakness allows an attacker who gains access to the backup repository to potentially substitute or modify the manifest file with forged content, making it appear as though legitimate archives exist or that certain archives have been removed when they actually remain accessible. The vulnerability specifically targets the cryptographic authentication process rather than the encryption of actual backup data, which means that while the encrypted backup content remains protected, the metadata that governs access to that content becomes compromised. This issue falls under the category of cryptographic protocol weakness as classified by CWE-310 and represents a failure in proper authentication mechanisms that could enable privilege escalation and data integrity violations.
The operational impact of this vulnerability extends beyond simple data corruption, as it fundamentally undermines the trust model that BorgBackup relies upon to provide secure backup services. When an attacker can spoof the manifest, they can potentially hide malicious activities, manipulate backup restoration processes, or create false impressions about the state of backup repositories. This vulnerability particularly affects organizations that depend on BorgBackup for critical data protection, as it could lead to undetected data tampering or unauthorized access to backup data. The implications are severe because backup systems are often considered trusted repositories of data, and compromising the manifest authentication creates a false sense of security that could delay detection of actual data breaches. From an attack perspective, this vulnerability aligns with ATT&CK technique T1566 which involves phishing and social engineering, but specifically targets the integrity of backup systems rather than user credentials or network access.
Mitigation strategies for CVE-2016-10099 primarily involve upgrading to BorgBackup version 1.0.9 or later, where the cryptographic authentication flaws have been addressed. Organizations should also implement additional monitoring mechanisms to detect unauthorized changes to manifest files, including regular integrity checks and cryptographic verification of manifest contents. Network segmentation and access controls should be strengthened to limit exposure of backup repositories to potential attackers. The fix implemented in version 1.0.9 specifically addresses the cryptographic protocol weakness by strengthening the authentication mechanism for manifest files, ensuring that any modification attempts are properly detected and rejected. Security teams should conduct comprehensive audits of their backup environments to verify that all BorgBackup instances have been updated and that proper integrity checking procedures are in place to prevent similar vulnerabilities from occurring in other components of their backup infrastructure.