CWE-196—Unsigned to Signed Conversion Error

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.

相关 CWE

• CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')High
• CWE-124Buffer Underwrite ('Buffer Underflow')Medium
• CWE-681Incorrect Conversion between Numeric TypesHigh