The product subtracts one value from another, such that the result is less than the minimum allowable integer value, which produces a value that is not equal to the correct result.
This can happen in signed and unsigned cases.
"Integer underflow" is sometimes used to identify signedness errors in which an originally positive number becomes negative as a result of subtraction. However, there are cases of bad subtraction in which unsigned integers are involved, so it's not always a signedness issue.
"Integer underflow" is occasionally used to describe array index errors in which the index is negative.
| Nature | Mapping | Type | ID | Name |
|---|---|---|---|---|
| ChildOf | Discouraged | P | 682 | Incorrect Calculation |
| Nature | Mapping | Type | ID | Name |
|---|---|---|---|---|
| MemberOf | Prohibited | C | 189 | Numeric Errors |
| MemberOf | Prohibited | V | 884 | CWE Cross-section |
| MemberOf | Prohibited | C | 998 | SFP Secondary Cluster: Glitch in Computation |
| MemberOf | Prohibited | C | 1137 | SEI CERT Oracle Secure Coding Standard for Java - Guidelines 03. Numeric Types and Operations (NUM) |
| MemberOf | Prohibited | C | 1158 | SEI CERT C Coding Standard - Guidelines 04. Integers (INT) |
| MemberOf | Prohibited | C | 1408 | Comprehensive Categorization: Incorrect Calculation |
| Nature | Mapping | Type | ID | Name |
|---|---|---|---|---|
| MemberOf | Prohibited | BS | BOSS-247 | Weaknesses in Software Written in C# |
| MemberOf | Prohibited | BS | BOSS-311 | Execute Unauthorized Code or Commands (impact) |
| MemberOf | Prohibited | BS | BOSS-314 | DoS: Resource Consumption (CPU) (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-327 | DoS: Resource Consumption (Memory) (impact) |
| MemberOf | Prohibited | BS | BOSS-329 | DoS: Instability (impact) |
| MemberOf | Prohibited | BS | BOSS-331 | Modify Memory (impact) |
| Nature | Mapping | Type | ID | Name |
|---|---|---|---|---|
| MemberOf | Prohibited | C | 1137 | SEI CERT Oracle Secure Coding Standard for Java - Guidelines 03. Numeric Types and Operations (NUM) |
| Nature | Mapping | Type | ID | Name |
|---|---|---|---|---|
| MemberOf | Prohibited | C | 1158 | SEI CERT C Coding Standard - Guidelines 04. Integers (INT) |
| Nature | Mapping | Type | ID | Name |
|---|---|---|---|---|
| MemberOf | Prohibited | C | 189 | Numeric Errors |
| 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 RestartDoS: Resource Consumption (CPU)DoS: Resource Consumption (Memory)DoS: Instability | This weakness will generally lead to undefined behavior and therefore crashes. In the case of overflows involving loop index variables, the likelihood of infinite loops is also high. |
| Integrity | N/A | Modify Memory | If the value in question is important to data (as opposed to flow), simple data corruption has occurred. Also, if the wrap around results in other conditions such as buffer overflows, further memory corruption may occur. |
| ConfidentialityAvailabilityAccess Control | N/A | Execute Unauthorized Code or CommandsBypass Protection Mechanism | This weakness 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. |
This weakness will generally lead to undefined behavior and therefore crashes. In the case of overflows involving loop index variables, the likelihood of infinite loops is also high.
If the value in question is important to data (as opposed to flow), simple data corruption has occurred. Also, if the wrap around results in other conditions such as buffer overflows, further memory corruption may occur.
This weakness 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.
N/A
The following example subtracts from a 32 bit signed integer.
The example has an integer underflow. The value of i is already at the lowest negative value possible, so after subtracting 1, the new value of i is 2147483647.
This code performs a stack allocation based on a length calculation.
Since a and b are declared as signed ints, the "a - b" subtraction gives a negative result (-1). However, since len is declared to be unsigned, len is cast to an extremely large positive number (on 32-bit systems - 4294967295). As a result, the buffer buf[len] declaration uses an extremely large size to allocate on the stack, very likely more than the entire computer's memory space.
Miscalculations usually will not be so obvious. The calculation will either be complicated or the result of an attacker's input to attain the negative value.
| Reference | Description |
|---|---|
| CVE-2004-0816 | Integer underflow in firewall via malformed packet. |
| CVE-2004-1002 | Integer underflow by packet with invalid length. |
| CVE-2005-0199 | Long input causes incorrect length calculation. |
| CVE-2005-1891 | Malformed icon causes integer underflow in loop counter variable. |
| Ordinality | Description |
|---|
Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)
N/A
This CWE entry is at the Base 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 |
|---|---|---|---|
| PLOVER | N/A | N/A | Integer underflow (wrap or wraparound) |
| Software Fault Patterns | SFP1 | N/A | Glitch in computation |
| CERT C Secure Coding | INT30-C | Imprecise | Ensure that unsigned integer operations do not wrap |
| CERT C Secure Coding | INT32-C | Imprecise | Ensure that operations on signed integers do not result in overflow |
| ID | Name |
|---|