CVE-2010-3495 in ZODB
Summary
by MITRE
Race condition in ZEO/StorageServer.py in Zope Object Database (ZODB) before 3.10.0 allows remote attackers to cause a denial of service (daemon outage) by establishing and then immediately closing a TCP connection, leading to the accept function having an unexpected return value of None, an unexpected value of None for the address, or an ECONNABORTED, EAGAIN, or EWOULDBLOCK error, a related issue to CVE-2010-3492.
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Analysis
by VulDB Data Team • 02/03/2018
The vulnerability identified as CVE-2010-3495 represents a critical race condition flaw within the Zope Object Database (ZODB) system, specifically in the ZEO/StorageServer.py component. This issue affects versions prior to 3.10.0 and demonstrates how seemingly benign network operations can lead to significant system instability. The vulnerability operates through a timing-dependent flaw that occurs during the TCP connection handling process, creating a window where the system's state becomes inconsistent and unpredictable.
The technical mechanism behind this vulnerability involves the interaction between the accept function and TCP connection management within the ZODB daemon. When remote attackers establish and immediately close TCP connections, the system encounters unexpected return values from the accept function, specifically receiving None instead of expected connection handles. Additionally, the address parameter may return None values, and the system may encounter ECONNABORTED, EAGAIN, or EWOULDBLOCK error conditions. These unexpected states occur due to the race condition where the connection handling logic does not properly account for the timing between connection establishment and termination, creating a scenario where the daemon's state machine becomes corrupted.
This race condition directly impacts system availability through a denial of service attack vector that can completely shut down the ZODB daemon. The attack requires minimal resources from the attacker, who only needs to establish and close TCP connections rapidly, making it particularly dangerous in production environments where such attacks could be executed continuously. The daemon outage occurs because the system cannot properly handle the unexpected connection states, leading to a cascade of failures in the connection management subsystem. The vulnerability is classified under CWE-362, which specifically addresses race conditions in software systems, and aligns with ATT&CK technique T1499.004 for network denial of service attacks.
The operational impact of this vulnerability extends beyond simple service interruption, as it can affect data integrity and system reliability within ZODB deployments. Organizations using affected versions of ZODB may experience complete service outages, potentially leading to data access failures and operational disruptions. The vulnerability's relationship to CVE-2010-3492 demonstrates that this represents part of a broader class of issues affecting ZODB's connection handling mechanisms. System administrators and security teams must recognize that this vulnerability can be exploited by attackers with minimal technical expertise, making it a significant concern for organizations relying on ZODB for critical data storage operations. The remediation approach requires immediate patching to version 3.10.0 or later, along with implementing connection rate limiting and monitoring to detect potential exploitation attempts.
Organizations should also consider implementing network-level protections such as connection throttling and firewall rules to limit the rate of connection attempts from individual sources. The vulnerability highlights the importance of proper error handling in network services and demonstrates how race conditions can create security issues beyond simple exploitation. System monitoring should be enhanced to detect unusual patterns in connection handling and daemon behavior, as these may indicate exploitation attempts. Additionally, the incident underscores the critical need for thorough testing of connection handling code, particularly in high-availability systems where denial of service attacks can have severe operational consequences.