CWE-124

Buffer Underwrite ('Buffer Underflow')

Base EXPLOIT LIKELIHOOD: MEDIUM

What it is

The product writes to a buffer using an index or pointer that references a memory location prior to the beginning of the buffer.

Integrity, Availability	Modify Memory, DoS: Crash, Exit, or Restart
Integrity, Confidentiality, Availability, Access Control, Other	Execute Unauthorized Code or Commands, Modify Memory, Bypass Protection Mechanism, Other
Access Control, Other	Bypass Protection Mechanism, Other

[Requirements] Choose a language that is not susceptible to these issues.
[Implementation] All calculated values that are used as index or for pointer arithmetic should be validated to ensure that they are within an expected range.

CVE-2021-24018 — buffer underwrite in firmware verification routine allows code execution via a crafted firmware image
CVE-2002-2227 — Unchecked length of SSLv2 challenge value leads to buffer underflow.
CVE-2007-4580 — Buffer underflow from a small size value with a large buffer (length parameter inconsistency, CWE-130)
CVE-2007-1584 — Buffer underflow from an all-whitespace string, which causes a counter to be decremented before the buffer while looking for a non-whitespace character.
CVE-2007-0886 — Buffer underflow resultant from encoded data that triggers an integer overflow.
CVE-2006-6171 — Product sets an incorrect buffer size limit, leading to "off-by-two" buffer underflow.
CVE-2006-4024 — Negative value is used in a memcpy() operation, leading to buffer underflow.
CVE-2004-2620 — Buffer underflow due to mishandled special characters

Test & detect