CWE-127: Buffer Under-read
The product reads from a buffer using buffer access mechanisms such as indexes or pointers that reference memory locations prior to the targeted buffer.
How it's found
Buffer Under-read is a specific, narrowly defined instance of a broader pattern. Testers confirm it with targeted code review and a proof-of-concept input that exercises the exact code path this weakness describes.
Vulnerable vs. safe
// check that the array index is less than the maximum
// length of the array
// if array index is invalid then output error message
// and return value indicating error
// get the value at the specified index of the arrayvalue = array[index];
printf("Value is: %d\n", array[index]);value = -1;int value;if (index < len) {}else {}return value;int getValueFromArray(int *array, int len, int index) {}// check that the array index is within the correct
// range of values for the array...if (index >= 0 && index < len) {...Consequences
- Read Memory
- Bypass Protection Mechanism: By reading out-of-bounds memory, an attacker might be able to get secret values, such as memory addresses, which can bypass protection mechanisms such as ASLR in order to improve the reliability and likelihood of exploiting a separate weakness to achieve code execution instead of just denial of service.
Where this fits in a TurboPentest engagement
TurboPentest's agentic pentest is powerful and covers a broad range of issues automatically. This particular class is best confirmed in a manual IntegSec engagement, where human pentesters apply deeper methodology and a larger context window than any automated pass.
Frequently asked questions
What is CWE-127?
The product reads from a buffer using buffer access mechanisms such as indexes or pointers that reference memory locations prior to the targeted buffer.
How do you find Buffer Under-read?
Buffer Under-read is a specific, narrowly defined instance of a broader pattern. Testers confirm it with targeted code review and a proof-of-concept input that exercises the exact code path this weakness describes.
What is the impact of CWE-127?
Read Memory Bypass Protection Mechanism: By reading out-of-bounds memory, an attacker might be able to get secret values, such as memory addresses, which can bypass protection mechanisms such as ASLR in order to improve the reliability and likelihood of exploiting a separate weakness to achieve code execution instead of just denial of service.
Does TurboPentest test for Buffer Under-read?
TurboPentest's agentic pentest is powerful and covers a broad range of issues automatically. This particular class is best confirmed in a manual IntegSec engagement, where human pentesters apply deeper methodology and a larger context window than any automated pass.
Related CWEs
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