CVE-2016-10724 in Bitcoin Core
Summary
by MITRE
Bitcoin Core before v0.13.0 allows denial of service (memory exhaustion) triggered by the remote network alert system (deprecated since Q1 2016) if an attacker can sign a message with a certain private key that had been known by unintended actors, because of an infinitely sized map. This affects other uses of the codebase, such as Bitcoin Knots before v0.13.0.knots20160814 and many altcoins.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 02/25/2020
The vulnerability CVE-2016-10724 represents a critical denial of service weakness in Bitcoin Core versions prior to 0.13.0 that stems from improper memory management within the network alert system. This flaw existed within a deprecated component that had been officially removed from the protocol since early 2016, yet remained functional in older codebases, creating a persistent security risk that affected not only the core Bitcoin implementation but also numerous derivative projects including Bitcoin Knots and various alternative cryptocurrencies. The vulnerability specifically targets the memory allocation mechanism used to store network alerts, where an attacker could exploit a design flaw that allowed for an infinitely growing map structure.
The technical implementation of this vulnerability resides in the improper handling of network alert messages within the Bitcoin Core codebase, where the system maintained an unbounded map structure to track alert messages received from the network. This map was designed to store alert identifiers and their associated metadata, but lacked proper bounds checking or memory limits that would prevent excessive growth. When an attacker possessed a private key that had been compromised or accidentally exposed, they could craft malicious network alert messages that would be accepted by the system and stored in this unbounded map. The attack vector specifically exploited the fact that the network alert system, although deprecated, remained active in older versions and did not properly validate the size or number of entries that could be stored in the alert tracking structure.
The operational impact of this vulnerability extends far beyond a simple denial of service condition, as it could lead to complete system exhaustion of available memory resources and subsequent node failures across the Bitcoin network. This memory exhaustion attack could be executed by a single malicious actor who controlled the compromised private key, potentially causing multiple nodes to crash or become unresponsive, thereby fragmenting the network and disrupting transaction propagation. The vulnerability's reach was particularly concerning because it affected not just Bitcoin Core but also numerous altcoin implementations that had inherited the same flawed code patterns, creating a widespread risk that could compromise the entire cryptocurrency ecosystem's network integrity and availability.
The root cause of this vulnerability aligns with CWE-770, which addresses the allocation of resources without proper limits or bounds checking, and demonstrates a classic example of insufficient resource management in security-critical systems. From an attack perspective, this vulnerability fits within the ATT&CK framework's privilege escalation and denial of service tactics, as it allows attackers to consume system resources in a manner that could lead to complete service disruption. The attack specifically leverages the network alert system's trust model, where legitimate network messages are accepted without adequate validation of their resource impact, and the fact that the system did not implement proper memory limits or garbage collection mechanisms for the alert tracking data structure. The vulnerability's persistence across multiple implementations highlights the importance of proper code review and the removal of deprecated functionality, as well as the necessity of implementing proper resource management and bounds checking in security-critical applications. This flaw ultimately demonstrated how legacy code patterns and deprecated features could continue to pose significant security risks even after their intended removal from the protocol, emphasizing the critical need for comprehensive security audits and proper deprecation practices in distributed systems.