CWE-242: Use of Inherently Dangerous Function

Description

The product calls a function that can never be guaranteed to work safely.

Submission Date :

July 19, 2006, midnight

Modification Date :

2023-06-29 00:00:00+00:00

Organization :

MITRE

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.

Example Vulnerable Codes

Example - 1

The code below calls gets() to read information into a buffer.


char buf[BUFSIZE];gets(buf);

The gets() function in C is inherently unsafe.

Example - 2

The code below calls the gets() function to read in data from the command line.


char buf[24];printf("Please enter your name and press <Enter>\n");gets(buf);...}

However, gets() is inherently unsafe, because it 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.

Related Weaknesses

This table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined to give an overview of the different insight to similar items that may exist at higher and lower levels of abstraction.

CWE-1177: Use of Prohibited Code

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