CWE-196 - Unsigned to Signed Conversion Error
- 摘要：Variant
- 结构：Simple
- 状态：Draft
- 发布日期：2006-07-19
- 更新日期：2025-12-11
名称
Unsigned to Signed Conversion Error
描述
The product uses an unsigned primitive and performs a cast to a signed primitive, which can produce an unexpected value if the value of the unsigned primitive can not be represented using a signed primitive.
Although less frequent an issue than signed-to-unsigned conversion, unsigned-to-signed conversion can be the perfect precursor to dangerous buffer underwrite conditions that allow attackers to move down the stack where they otherwise might not have access in a normal buffer overflow condition. Buffer underwrites occur frequently when large unsigned values are cast to signed values, and then used as indexes into a buffer or for pointer arithmetic.
常见后果
范围：Availability
影响：DoS: Crash, Exit, or Restart
注释：Incorrect sign conversions generally lead to undefined behavior, and therefore crashes.
范围：Integrity
影响：Modify Memory
注释：If a poor cast lead to a buffer overflow or similar condition, data integrity may be affected.
范围：Integrity, Confidentiality, Availability, Access Control
影响：Execute Unauthorized Code or Commands, Bypass Protection Mechanism
注释：Improper signed-to-unsigned conversions without proper checking can sometimes trigger buffer overflows which can be used to execute arbitrary code. This is usually outside the scope of a program's implicit security policy.