The program calls a function that can never be guaranteed to work safely.
Extended Description
Certain functions behave in dangerous ways regardless of how they are used. Functions in this category were often implemented without taking security concerns into account. The gets() function is unsafe because it does not perform bounds checking on the size of its input. An attacker can easily send arbitrarily-sized input to gets() and overflow the destination buffer. Similarly, the >> operator is unsafe to use when reading into a statically-allocated character array because it does not perform bounds checking on the size of its input. An attacker can easily send arbitrarily-sized input to the >> operator and overflow the destination buffer.
Time of Introduction
Implementation
Applicable Platforms
Languages
C
C++
Common Consequences
Scope
Effect
Other
Technical Impact: Varies by context
Likelihood of Exploit
High
Demonstrative Examples
Example 1
The excerpt below calls the gets() function in C, which is
inherently unsafe.
(Bad Code)
Example
Language: C
char buf[BUFSIZE];
gets(buf);
Example 2
The excerpt below calls the gets() function in C, which is
inherently unsafe.
(Bad Code)
Example
Language: C
char buf[24];
printf("Please enter your name and press
<Enter>\n");
gets(buf);
...
}
However, the programmer uses the function gets() which is inherently
unsafe because it blindly copies all input from STDIN to the buffer
without checking size. This allows the user to provide a string that is
larger than the buffer size, resulting in an overflow condition.
Potential Mitigations
Phases: Implementation; Requirements
Ban the use of dangerous functions. Use their safe equivalent.
Phase: Testing
Use grep or static analysis tools to spot usage of dangerous
functions.
Weakness Ordinalities
Ordinality
Description
Primary
(where
the weakness exists independent of other weaknesses)
Description
