Alternative functions that limit the number of bytes copied are often recommended to mitigate buffer overflow vulnerabilities. For example:
strncpy()
instead ofstrcpy()
strncat()
instead ofstrcat()
fgets()
instead ofgets()
snprintf()
instead ofsprintf()
These functions truncate strings that exceed the specified limits. Additionally, some functions such as strncpy()
do not guarantee that the resulting string is null-terminated [[STR32-C. Null-terminate byte strings as required]].
Unintentional truncation results in a loss of data and, in some cases, leads to software vulnerabilities.
Exceptions
An exception to this rule applies if the intent of the programmer was to intentionally truncate the null-terminated byte string.
Risk Assessment
Truncating strings can lead to a loss of data.
Recommendation |
Severity |
Likelihood |
Remediation Cost |
Priority |
Level |
---|---|---|---|---|---|
STR03-A |
1 (low) |
1 (unlikely) |
2 (medium) |
P2 |
L3 |
Related Vulnerabilities
Search for vulnerabilities resulting from the violation of this rule on the CERT website.
References
[[ISO/IEC 9899-1999]] Section 7.21, "String handling <string.h>"
[[Seacord 05a]] Chapter 2, "Strings"
[[ISO/IEC TR 24731-1-2007]]