CWE-170
Improper Null Termination
AI Translation Available
The product does not terminate or incorrectly terminates a string or array with a null character or equivalent terminator.
Status
incomplete
Abstraction
base
Likelihood
medium
Affected Platforms
C
C++
Extended Description
AI Translation
Null termination errors frequently occur in two different ways. An off-by-one error could cause a null to be written out of bounds, leading to an overflow. Or, a program could use a strncpy() function call incorrectly, which prevents a null terminator from being added at all. Other scenarios are possible.
Technical Details
AI Translation
Common Consequences
confidentiality
integrity
availability
access control
other
Impacts
read memory
execute unauthorized code or commands
dos: crash, exit, or restart
dos: resource consumption (cpu)
dos: resource consumption (memory)
modify memory
alter execution logic
Detection Methods
automated static analysis
Potential Mitigations
Phases:
requirements
implementation
Descriptions:
•
Use a language that is not susceptible to these issues. However, be careful of null byte interaction errors (CWE-626) with lower-level constructs that may be written in a language that is susceptible.
•
Ensure that all string functions used are understood fully as to how they append null characters. Also, be wary of off-by-one errors when appending nulls to the end of strings.
•
If performance constraints permit, special code can be added that validates null-termination of string buffers, this is a rather naive and error-prone solution.
•
Switch to bounded string manipulation functions. Inspect buffer lengths involved in the buffer overrun trace reported with the defect.
•
Add code that fills buffers with nulls (however, the length of buffers still needs to be inspected, to ensure that the non null-terminated string is not written at the physical end of the buffer).