CWE-170
Improper Null Termination
Description
The product does not terminate or incorrectly terminates a string or array with a null character or equivalent terminator.
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.
Parent Weaknesses (ChildOf)
Common Consequences
Scope
Impact
Read Memory, Execute Unauthorized Code or Commands
Scope
Impact
DoS: Crash, Exit, or Restart, Read Memory, DoS: Resource Consumption (CPU), DoS: Resource Consumption (Memory)
Scope
Impact
Modify Memory, DoS: Crash, Exit, or Restart
Scope
Impact
Alter Execution Logic, Execute Unauthorized Code or Commands
Potential Mitigations
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).
CVE-2000-0312Attacker does not null-terminate argv[] when invoking another program.
CVE-2003-0777Interrupted step causes resultant lack of null termination.
CVE-2004-1072Fault causes resultant lack of null termination, leading to buffer expansion.
CVE-2001-1389Multiple vulnerabilities related to improper null termination.
CVE-2003-0143Product does not null terminate a message buffer after snprintf-like call, leading to overflow.
CVE-2009-2523Chain: product does not handle when an input string is not NULL terminated (CWE-170), leading to buffer over-read (CWE-125) or heap-based buffer overflow (CWE-122).
Applicable Platforms
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