CVE-2005-4883 in Tftpd32
Summary
by MITRE
Race condition in Philippe Jounin Tftpd32 before 2.80 allows remote attackers to cause a denial of service (daemon crash) via invalid "connect frames."
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Analysis
by VulDB Data Team • 01/23/2019
The vulnerability identified as CVE-2005-4883 represents a critical race condition flaw within the Tftpd32 network daemon version 2.79 and earlier. This issue stems from improper handling of network connections during the transfer process, specifically when processing invalid connect frames that are sent by remote attackers. The race condition occurs when multiple threads or processes attempt to access shared resources simultaneously without proper synchronization mechanisms, creating a window where the system becomes unstable and susceptible to exploitation.
This vulnerability operates at the network protocol level and specifically targets the Trivial File Transfer Protocol implementation within the Tftpd32 software. The flaw manifests when the daemon receives malformed connect frames that trigger an improper state transition in the connection handling logic. These invalid frames exploit timing dependencies in the software's state machine, allowing attackers to manipulate the daemon into entering an inconsistent state that ultimately leads to a crash. The race condition aspect means that the timing of operations between different threads becomes critical to the exploit's success, making this a sophisticated attack vector that requires precise timing and understanding of the internal software architecture.
The operational impact of this vulnerability extends beyond simple denial of service, as it can be leveraged to disrupt network services and potentially create opportunities for further exploitation. When the daemon crashes, legitimate users lose access to file transfer services, which can have cascading effects on network operations and system availability. This type of vulnerability is particularly concerning in environments where Tftpd32 is used for critical file distribution or as part of network infrastructure components. The vulnerability aligns with CWE-362, which describes race conditions in software systems where concurrent execution can lead to unpredictable behavior and security issues. From an attack framework perspective, this vulnerability could be categorized under the MITRE ATT&CK technique T1499.004, which involves network denial of service attacks targeting specific network services.
The technical implementation of this vulnerability demonstrates poor resource management and inadequate input validation within the Tftpd32 daemon. When invalid connect frames are received, the software fails to properly validate the frame structure and timing, allowing malformed data to interfere with the connection establishment process. The lack of proper mutex locks or synchronization primitives during critical sections of code means that concurrent access to shared connection state variables can result in corrupted data structures or invalid memory access patterns. This vulnerability represents a classic example of how insufficient concurrency control can lead to system instability and potential security breaches in network services. The fix for this vulnerability required implementing proper synchronization mechanisms and enhanced input validation to ensure that the daemon could gracefully handle malformed network frames without crashing, thereby maintaining service availability and system stability.