CVE-2019-15947 in Bitcoin Core
Summary
by MITRE
In Bitcoin Core 0.18.0, bitcoin-qt stores wallet.dat data unencrypted in memory. Upon a crash, it may dump a core file. If a user were to mishandle a core file, an attacker can reconstruct the user's wallet.dat file, including their private keys, via a grep "6231 0500" command.
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Analysis
by VulDB Data Team • 12/13/2023
The vulnerability described in CVE-2019-15947 represents a critical security flaw in Bitcoin Core version 0.18.0 that exposes private keys through improper memory handling during application crashes. This issue specifically affects the bitcoin-qt graphical user interface component of the Bitcoin client where wallet data is stored in an unencrypted format within the application's memory space. The vulnerability arises from the application's failure to properly secure sensitive cryptographic information during runtime operations, creating a persistent exposure that extends beyond normal operational boundaries into crash recovery scenarios.
The technical implementation of this flaw stems from how Bitcoin Core handles memory management when the application encounters a crash condition. When bitcoin-qt terminates unexpectedly, it may generate a core dump file that contains the complete memory state of the running process. These core files retain the unencrypted wallet.dat data in memory, including all private keys and wallet information that should remain protected. The vulnerability is particularly concerning because the memory layout of the application includes recognizable patterns that make recovery straightforward for attackers. The specific grep pattern "6231 0500" serves as a signature that allows attackers to identify and extract the wallet data from core files, effectively bypassing normal encryption protections.
This vulnerability creates significant operational impact for Bitcoin users who may not fully understand the security implications of core file handling or who may inadvertently share or expose core dump files. The attack vector requires minimal technical expertise since it relies on standard Unix/Linux memory dump analysis tools and common pattern matching techniques. The exposure of private keys through this mechanism can result in complete financial loss for affected users, as attackers can immediately access and control all funds stored in the compromised wallet. The vulnerability affects all users who utilize the bitcoin-qt interface with wallet.dat files, making it particularly widespread in the Bitcoin ecosystem.
The security implications of this vulnerability align with CWE-310 (Cryptographic Issues) and represent a failure in proper memory sanitization and secure coding practices. From an attacker's perspective, this vulnerability maps to ATT&CK technique T1005 (Data from Local System) and T1021.002 (Remote Services) as it allows for the extraction of sensitive data through local memory analysis. The flaw demonstrates poor adherence to security best practices regarding temporary data handling and memory protection during abnormal termination conditions. Organizations and individuals using Bitcoin Core should immediately upgrade to versions that address this vulnerability and implement proper core file management policies to prevent accidental exposure of sensitive information.
Mitigation strategies for this vulnerability include upgrading to Bitcoin Core versions that properly handle memory cleanup during application termination, implementing strict core file permission controls, and establishing secure disposal procedures for core dump files. System administrators should configure core file limits and disable automatic core dumps in production environments where Bitcoin wallets are used. Users should also be educated about the security implications of core file handling and the importance of secure file management practices. The vulnerability underscores the critical need for comprehensive memory protection mechanisms in cryptocurrency applications and highlights the importance of secure coding practices that consider all possible termination scenarios including crashes and abnormal exits.