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CWE-170

不適切なヌル・ターミネーション

Improper Null Termination

脆弱性作成中

日本語説明

JA

製品が文字列または配列をヌル文字または同等の終端記号で終端していないか、または誤って終端しています。

ヌル終了エラーは、2つの異なる方法で頻繁に発生する。1個ずつのエラーによってNULLが境界外に書き込まれ、オーバーフローを引き起こす可能性がある。あるいは、プログラムがstrncpy()関数コールを誤って使用し、ヌル・ターミネータがまったく追加されないようにする。その他のシナリオも考えられる。

原文 (English)

EN

The product does not terminate or incorrectly terminates a string or array with a null character or equivalent terminator.

Null termination errors frequently occur in two different ways. An off-by-one error could cause a null to be written out of bounds, leading to an overflow. Or, a program could use a strncpy() function call incorrectly, which prevents a null terminator from being added at all. Other scenarios are possible.

関連する脆弱性

想定される影響

Scope: Confidentiality, Integrity, Availability / Impact: Read Memory; Execute Unauthorized Code or Commands

Scope: Confidentiality, Integrity, Availability / Impact: DoS: Crash, Exit, or Restart; Read Memory; DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory)

Scope: Integrity, Availability / Impact: Modify Memory; DoS: Crash, Exit, or Restart

Scope: Integrity, Confidentiality, Availability, Access Control, Other / Impact: Alter Execution Logic; Execute Unauthorized Code or Commands

対策・緩和策

Use a language that is not susceptible to these issues. However, be careful of null byte interaction errors (CWE-626) with lower-level constructs that may be written in a language that is susceptible.

Ensure that all string functions used are understood fully as to how they append null characters. Also, be wary of off-by-one errors when appending nulls to the end of strings.

If performance constraints permit, special code can be added that validates null-termination of string buffers, this is a rather naive and error-prone solution.

Switch to bounded string manipulation functions. Inspect buffer lengths involved in the buffer overrun trace reported with the defect.

Add code that fills buffers with nulls (however, the length of buffers still needs to be inspected, to ensure that the non null-terminated string is not written at the physical end of the buffer).

外部リンク

MITRE公式ページ — CWE-170