Authorization / Improper Restriction of Operations within the Bounds of a Memory Buffer

Description

Improper Restriction of Operations within the Bounds of a Memory Buffer (CWE-119) is a type of Authorization vulnerability that occurs when a program does not properly limit operations within the bounds of a memory buffer. This can lead to a situation where the program reads from or writes to memory outside of the allocated buffer and can cause memory corruption. According to the CWE directory, this type of vulnerability is listed in the CWE Top 25 (2022) for both Web and API applications.

Risk

Improper Restriction of Operations within the Bounds of a Memory Buffer is a high severity vulnerability as it can lead to memory corruption and serious security flaws. If left unaddressed, it can lead to the disclosure of sensitive information, unauthorized access to the system, and denial of service.

Solution

The best way to address this vulnerability is to ensure that all operations are properly limited within the bounds of a memory buffer. This can be done by defining the size of the buffer when initializing the buffer and validating the size of the buffer before performing any operations. Additionally, the OWASP Testing Guide recommends that developers use built-in functions such as strcpy_s(), strncpy_s(), strcat_s() and strncat_s() when copying strings.

Example

char buf[128];
strncpy(buf, input, sizeof(buf));

In the example above, the program is using the strncpy() function to copy a string from the variable “input” to the buffer “buf”. However, it is not validating the size of the buffer before performing the copy. This could lead to a buffer overflow and memory corruption if the size of the input is greater than the size of the buffer.