![]() ![]() Pillar - a weakness that is the most abstract type of weakness and represents a theme for all class/base/variant weaknesses related to it. An untrusted interfering code sequence can be authored directly by the attacker, and typically it is external to the vulnerable program. The interfering code sequence could be "trusted" or "untrusted." A trusted interfering code sequence occurs within the program it cannot be modified by the attacker, and it can only be invoked indirectly. For example, the single "x++" statement may appear atomic at the code layer, but it is actually non-atomic at the instruction layer, since it involves a read (the original value of x), followed by a computation (x+1), followed by a write (save the result to x). Programmers may assume that certain code sequences execute too quickly to be affected by an interfering code sequence when they are not, this violates atomicity. Atomicity - the code sequence is behaviorally atomic, i.e., no other thread or process can concurrently execute the same sequence of instructions (or a subset) against the same resource.Ī race condition exists when an "interfering code sequence" can still access the shared resource, violating exclusivity.Exclusivity - the code sequence is given exclusive access to the shared resource, i.e., no other code sequence can modify properties of the shared resource before the original sequence has completed execution. ![]() Depending on the context, a code sequence may be in the form of a function call, a small number of instructions, a series of program invocations, etc.Ī race condition violates these properties, which are closely related: ![]() This can have security implications when the expected synchronization is in security-critical code, such as recording whether a user is authenticated or modifying important state information that should not be influenced by an outsider.Ī race condition occurs within concurrent environments, and is effectively a property of a code sequence. ![]()
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