CVE-2013-2273 in bitcoind
Summary
by MITRE
bitcoind and Bitcoin-Qt before 0.4.9rc1, 0.5.x before 0.5.8rc1, 0.6.0 before 0.6.0.11rc1, 0.6.1 through 0.6.5 before 0.6.5rc1, and 0.7.x before 0.7.3rc1 make it easier for remote attackers to obtain potentially sensitive information about returned change by leveraging certain predictability in the outputs of a Bitcoin transaction.
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Analysis
by VulDB Data Team • 02/25/2019
The vulnerability described in CVE-2013-2273 represents a significant privacy and security flaw in early versions of the Bitcoin blockchain software ecosystem. This issue affects multiple major release branches including 0.4.x, 0.5.x, 0.6.x, and 0.7.x versions prior to their respective patch releases. The core problem lies in the predictable patterns of change outputs within Bitcoin transactions, which creates information leakage that can be exploited by remote attackers to gain insights into transaction structures and potentially identify user spending patterns.
The technical flaw stems from the deterministic nature of how Bitcoin clients generate change addresses during transaction processing. When users make transactions, the software creates change outputs that represent the remaining balance after deducting the transaction amount and fees. In vulnerable versions, this process exhibited predictable patterns that allowed attackers to correlate transaction inputs with outputs, particularly when multiple transactions were processed through the same wallet. The predictability emerged from the way change addresses were generated and the patterns in transaction fee calculations, creating a side-channel attack vector that could be exploited to infer information about user behavior and wallet balance movements.
This vulnerability operates at the intersection of privacy preservation and cryptographic security within blockchain systems, aligning with CWE-200 (Information Exposure) and representing a significant threat to user anonymity. The operational impact extends beyond simple information leakage to potentially enable sophisticated tracking of user activities across the blockchain network. Attackers could use this information to construct behavioral profiles of users, identify transaction patterns, and potentially correlate wallet addresses with real-world identities. The vulnerability particularly affects users who engage in frequent transactions or maintain wallets with multiple addresses, as the predictability becomes more pronounced with increased transaction volume.
The implications of this vulnerability are particularly concerning given the fundamental privacy expectations users have when transacting with Bitcoin. The issue creates a scenario where the very mechanism designed to maintain transaction integrity and wallet security becomes a vector for information disclosure. From an attacker perspective, this vulnerability enables techniques that fall under the MITRE ATT&CK framework's T1589 (Compromise Client Software Binary) and T1071 (Application Layer Protocol) categories, as it exploits weaknesses in client-side transaction processing and network communication patterns. The attack surface is particularly wide given that the vulnerability affects multiple major versions of both the command-line and graphical interfaces of the Bitcoin software.
Mitigation strategies for CVE-2013-2273 require immediate software updates to patched versions including 0.4.9rc1, 0.5.8rc1, 0.6.0.11rc1, 0.6.5rc1, and 0.7.3rc1. Users should also implement additional protective measures such as using fresh addresses for each transaction, avoiding transaction clustering, and employing more sophisticated privacy-enhancing techniques like CoinJoin operations. The vulnerability highlights the importance of proper randomization in cryptographic systems and demonstrates how seemingly minor implementation details can create significant security risks. Organizations and individuals relying on Bitcoin services should conduct thorough security assessments of their wallet implementations and ensure all systems are updated to versions that address this specific information disclosure vulnerability.