CVE-2012-1909 in bitcoind
Summary
by MITRE
The Bitcoin protocol, as used in bitcoind before 0.4.4, wxBitcoin, Bitcoin-Qt, and other programs, does not properly handle multiple transactions with the same identifier, which allows remote attackers to cause a denial of service (unspendable transaction) by leveraging the ability to create a duplicate coinbase transaction.
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Analysis
by VulDB Data Team • 12/07/2021
The vulnerability described in CVE-2012-1909 represents a critical flaw in the Bitcoin protocol implementation that affects multiple client software versions including bitcoind before 0.4.4 and wxBitcoin. This issue stems from the protocol's inadequate handling of transaction identifiers, specifically when duplicate transactions with identical identifiers are processed. The flaw creates a condition where malicious actors can exploit the system's transaction validation mechanism to generate a denial of service attack that results in unspendable transactions within the blockchain network.
The technical nature of this vulnerability resides in the protocol's failure to properly validate transaction uniqueness during the mining and transaction processing phases. When multiple transactions share the same identifier, particularly coinbase transactions that are fundamental to the blockchain's creation process, the affected implementations do not adequately distinguish between legitimate and duplicate transactions. This oversight allows attackers to submit duplicate coinbase transactions that can cause the system to incorrectly process these transactions, leading to a state where funds become permanently unspendable. The vulnerability operates at the core level of Bitcoin's transaction processing, where the identifier validation mechanism fails to prevent duplicate entries from being accepted into the transaction pool or blockchain.
The operational impact of this vulnerability extends beyond simple denial of service, creating a more severe condition where transaction funds become irretrievable within the network. When duplicate coinbase transactions are processed, they can corrupt the transaction state, making the associated bitcoins unspendable while appearing to be valid transactions within the blockchain. This condition affects the entire network's integrity as it creates invalid transaction states that can propagate through the system. The vulnerability is particularly dangerous because coinbase transactions are essential for creating new bitcoins and maintaining the blockchain's ledger, making this a fundamental threat to the protocol's core functionality. The attack vector leverages the ability to create duplicate transactions that exploit the protocol's lack of proper duplicate detection mechanisms, effectively allowing attackers to consume network resources while simultaneously creating permanent transaction corruption.
Mitigation strategies for CVE-2012-1909 require immediate implementation of protocol updates that enhance transaction identifier validation and introduce proper duplicate transaction detection mechanisms. Software vendors must implement robust transaction uniqueness checks that prevent duplicate identifiers from being processed, particularly for coinbase transactions that are critical to network operations. The fix should include comprehensive validation routines that examine transaction hashes and identifiers before accepting transactions into the processing pipeline. This vulnerability aligns with CWE-129, which addresses improper validation of input, and relates to ATT&CK technique T1499.004 for resource hijacking through denial of service attacks. Network administrators should also implement transaction filtering mechanisms that can identify and reject duplicate transaction attempts before they can cause network-wide disruption. The updated implementations must ensure that transaction processing maintains the integrity of the blockchain by preventing any transaction with duplicate identifiers from being accepted, thereby protecting the network from both immediate denial of service and long-term transaction corruption that renders funds permanently inaccessible.