Signal Handler Race Condition vulnerability in Mitsubishi Electric India GC-ENET-COM whose first 2 digits of 11-digit serial number of unit are 16 allows a remote unauthenticated attacker to cause a denial-of-service (DoS) condition in Ethernet communication by sending a large number of specially crafted packets to any UDP port when GC-ENET-COM is configured as a Modbus TCP Server. The communication resumes only when the power of the main unit is turned off and on or when the GC-ENET-COM is hot-swapped from the main unit.
The product uses a signal handler that introduces a race condition.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Gc-enet-com_firmware | Mitsubishielectric | - (including) | - (including) |
Race conditions frequently occur in signal handlers, since signal handlers support asynchronous actions. These race conditions have a variety of root causes and symptoms. Attackers may be able to exploit a signal handler race condition to cause the product state to be corrupted, possibly leading to a denial of service or even code execution. These issues occur when non-reentrant functions, or state-sensitive actions occur in the signal handler, where they may be called at any time. These behaviors can violate assumptions being made by the “regular” code that is interrupted, or by other signal handlers that may also be invoked. If these functions are called at an inopportune moment - such as while a non-reentrant function is already running - memory corruption could occur that may be exploitable for code execution. Another signal race condition commonly found occurs when free is called within a signal handler, resulting in a double free and therefore a write-what-where condition. Even if a given pointer is set to NULL after it has been freed, a race condition still exists between the time the memory was freed and the pointer was set to NULL. This is especially problematic if the same signal handler has been set for more than one signal – since it means that the signal handler itself may be reentered. There are several known behaviors related to signal handlers that have received the label of “signal handler race condition”:
Signal handler vulnerabilities are often classified based on the absence of a specific protection mechanism, although this style of classification is discouraged in CWE because programmers often have a choice of several different mechanisms for addressing the weakness. Such protection mechanisms may preserve exclusivity of access to the shared resource, and behavioral atomicity for the relevant code: