CVE-2010-3492 in Python
Summary
by MITRE
The asyncore module in Python before 3.2 does not properly handle unsuccessful calls to the accept function, and does not have accompanying documentation describing how daemon applications should handle unsuccessful calls to the accept function, which makes it easier for remote attackers to conduct denial of service attacks that terminate these applications via network connections.
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Analysis
by VulDB Data Team • 01/20/2025
The vulnerability identified as CVE-2010-3492 resides within Python's asyncore module, a core component designed for asynchronous socket operations that enables efficient handling of multiple network connections. This module serves as the foundation for many daemon applications and network services that rely on asynchronous I/O processing to maintain high performance while managing numerous concurrent connections. The flaw specifically manifests when the accept function fails during socket connection establishment, creating a scenario where the module lacks proper error handling mechanisms to gracefully manage these failures. The absence of comprehensive documentation regarding how daemon applications should properly handle such unsuccessful accept calls represents a significant gap in the module's operational guidance, leaving developers vulnerable to implementing insecure patterns that could be exploited by malicious actors.
The technical implementation flaw stems from the asyncore module's failure to adequately process error conditions returned by the underlying operating system's accept system call. When network connections fail or are rejected during the accept phase, the module does not properly account for these failures, potentially causing the application to terminate unexpectedly. This behavior creates a predictable attack surface where remote adversaries can craft specific network requests designed to trigger these error conditions, leading to application crashes and subsequent denial of service. The vulnerability is particularly dangerous in daemon applications where continuous availability is critical, as a single malicious connection attempt could bring down the entire service. The lack of proper error handling means that when accept calls fail due to resource exhaustion, network interruptions, or malicious input, the application cannot recover gracefully and instead terminates, providing attackers with a reliable method for service disruption.
The operational impact of this vulnerability extends beyond simple service interruption, as it fundamentally compromises the reliability and stability of applications built using the asyncore module. Attackers can systematically exploit this weakness by initiating connection attempts that are designed to trigger the specific error conditions that cause the module to fail. This creates a denial of service scenario where legitimate users cannot establish connections while the service remains unavailable. The vulnerability affects Python versions prior to 3.2, meaning that many legacy applications and systems continue to be at risk, particularly in enterprise environments where upgrading Python versions may be complex or delayed. The ease with which this vulnerability can be exploited makes it particularly attractive to attackers, as it requires minimal sophistication to implement and can cause significant disruption to network services that depend on asynchronous socket handling.
The mitigation strategies for this vulnerability involve both immediate and long-term approaches to address the underlying issue. The most direct solution is to upgrade to Python 3.2 or later versions where the asyncore module has been properly updated to handle accept function failures gracefully. Organizations should also implement proper error handling patterns in their applications that account for potential socket connection failures, ensuring that applications can recover from error conditions without terminating. Additionally, network-level protections such as connection rate limiting and proper firewall configurations can help reduce the impact of these attacks by preventing the rapid succession of connection attempts that could trigger the vulnerability. From a security standards perspective, this vulnerability aligns with CWE-248, which addresses the issue of an exception not being handled properly, and maps to ATT&CK technique T1499.1 for the specific denial of service attack vector. Organizations should also consider implementing monitoring and alerting systems that can detect unusual connection patterns or application termination events that may indicate exploitation attempts.
This vulnerability represents a classic example of how seemingly minor implementation flaws in core system components can create significant security risks. The asyncore module's failure to properly handle error conditions demonstrates the critical importance of robust error handling in network applications, particularly those serving as daemons or background services. The lack of proper documentation for developers compounds the issue, as it leaves implementation decisions to individual programmers who may not fully understand the implications of different error handling approaches. Modern secure coding practices emphasize the need for comprehensive error handling and graceful degradation, which this vulnerability highlights as essential requirements for maintaining service availability and preventing exploitation by malicious actors. The lessons learned from CVE-2010-3492 continue to influence secure development practices, particularly in the design of asynchronous network applications and the importance of considering failure modes in system architecture.