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.
| Nature | Mapping | Type | ID | Name |
|---|---|---|---|---|
| CanAlsoBe | Allowed | B | 124 | Buffer Underwrite ('Buffer Underflow') |
| CanAlsoBe | Allowed-with-Review | B | 120 | Buffer Copy without Checking Size of Input ('Classic Buffer Overflow') |
| ChildOf | Allowed | B | 681 | Incorrect Conversion between Numeric Types |
| ParentOf | Allowed | B | 197 | Numeric Truncation Error |
| Nature | Mapping | Type | ID | Name |
|---|---|---|---|---|
| MemberOf | Prohibited | C | 998 | SFP Secondary Cluster: Glitch in Computation |
| MemberOf | Prohibited | C | 1416 | Comprehensive Categorization: Resource Lifecycle Management |
| Nature | Mapping | Type | ID | Name |
|---|---|---|---|---|
| MemberOf | Prohibited | BS | BOSS-273 | Medium likelihood of exploit |
| MemberOf | Prohibited | BS | BOSS-311 | Execute Unauthorized Code or Commands (impact) |
| MemberOf | Prohibited | BS | BOSS-316 | Bypass Protection Mechanism (impact) |
| MemberOf | Prohibited | BS | BOSS-324 | DoS: Crash, Exit, or Restart (impact) |
| MemberOf | Prohibited | BS | BOSS-331 | Modify Memory (impact) |
| Nature | Mapping | Type | ID | Name |
|---|---|---|---|---|
| MemberOf | Prohibited | C | 998 | SFP Secondary Cluster: Glitch in Computation |
| Scope | Likelihood | Impact | Note |
|---|---|---|---|
| Availability | N/A | DoS: Crash, Exit, or Restart | Incorrect sign conversions generally lead to undefined behavior, and therefore crashes. |
| Integrity | N/A | Modify Memory | If a poor cast lead to a buffer overflow or similar condition, data integrity may be affected. |
| IntegrityConfidentialityAvailabilityAccess Control | N/A | Execute Unauthorized Code or CommandsBypass Protection Mechanism | 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. |
Incorrect sign conversions generally lead to undefined behavior, and therefore crashes.
If a poor cast lead to a buffer overflow or similar condition, data integrity may be affected.
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.
Choose a language which is not subject to these casting flaws.
Design object accessor functions to implicitly check values for valid sizes. Ensure that all functions which will be used as a size are checked previous to use as a size. If the language permits, throw exceptions rather than using in-band errors.
Error check the return values of all functions. Be aware of implicit casts made, and use unsigned variables for sizes if at all possible.
N/A
| Reference | Description |
|---|
| Ordinality | Description |
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This CWE entry is at the Variant level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.
| Taxonomy Name | Entry ID | Fit | Entry Name |
|---|---|---|---|
| CLASP | N/A | N/A | Unsigned to signed conversion error |
| Software Fault Patterns | SFP1 | N/A | Glitch in computation |