CVE-2015-4082 in attic
Summary
by MITRE
attic before 0.15 does not confirm unencrypted backups with the user, which allows remote attackers with read and write privileges for the encrypted repository to obtain potentially sensitive information by changing the manifest type byte of the repository to "unencrypted / without key file".
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Analysis
by VulDB Data Team • 12/16/2022
The vulnerability described in CVE-2015-4082 affects the attic backup tool version 0.15 and earlier, representing a critical security flaw in how the system handles repository encryption states. This issue stems from inadequate validation mechanisms that fail to properly confirm the encryption status of backup repositories before allowing data operations. The flaw exists in the repository manifest handling process where the system does not enforce proper verification of encryption parameters, creating a pathway for malicious actors to exploit the system's trust model.
The technical implementation of this vulnerability involves manipulation of the repository manifest type byte, which serves as a critical indicator of the backup's encryption status. When an attacker possesses read and write privileges to an encrypted repository, they can directly modify the manifest type byte to transition the repository state from encrypted to unencrypted. This modification effectively bypasses the normal encryption verification procedures that should occur during repository access operations. The change in manifest type byte allows the attacker to access backup data without proper decryption keys, as the system no longer recognizes the repository as requiring encryption. This represents a fundamental failure in the cryptographic integrity checking mechanisms and violates core principles of secure backup management.
The operational impact of this vulnerability extends beyond simple information disclosure, as it creates a persistent backdoor for unauthorized access to sensitive backup data. Attackers can exploit this flaw to gain access to potentially confidential information stored in backup repositories without requiring legitimate encryption keys or authentication credentials. The vulnerability particularly affects environments where backup systems are not properly secured or monitored, as the attack can be executed silently without alerting system administrators to the unauthorized access. This creates a significant risk for organizations relying on attic for backup operations, as it undermines the fundamental security assumptions of encrypted data protection. The vulnerability also aligns with attack patterns documented in the attack technique matrix where adversaries attempt to manipulate system state information to bypass security controls.
The root cause of this vulnerability can be classified under CWE-310, Cryptographic Issues, specifically related to improper validation of cryptographic parameters. The flaw represents a failure in the cryptographic protocol implementation where the system does not properly validate the consistency between the repository manifest and the actual encryption state. This type of vulnerability falls into the category of insecure cryptographic implementation as defined by the NIST SP 800-57 standard, which emphasizes the importance of proper cryptographic parameter validation. Organizations should implement proper repository state validation mechanisms that ensure manifest integrity and cryptographic consistency. The vulnerability demonstrates a lack of proper input validation and state management controls that should be implemented according to security best practices outlined in ISO/IEC 27001 and other security frameworks.
Mitigation strategies for this vulnerability should include immediate patching of attic to version 0.15 or later where the encryption state validation has been properly implemented. System administrators should also implement additional monitoring controls to detect unauthorized changes to repository manifest files, particularly focusing on the manifest type byte modifications. Access controls should be strengthened to ensure that only authorized personnel have write privileges to encrypted repositories, implementing principle of least privilege. The implementation of cryptographic integrity checks and digital signatures for repository manifests would provide additional layers of protection against unauthorized modifications. Organizations should also consider implementing automated repository state verification procedures that can detect inconsistencies between manifest declarations and actual cryptographic state, providing early warning capabilities for potential exploitation attempts.