CWE-192: Integer Coercion Error
Official CWE-192 CWE context with Glexia analysis, remediation guidance, related CVEs, and ATT&CK context.
Glexia's Take
CWE-192: Integer Coercion Error
Integer Coercion Error represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Executive Impact
- Availability: DoS: Resource Consumption (CPU),DoS: Resource Consumption (Memory),DoS: Crash, Exit, or Restart: Integer coercion often leads to undefined states of execution resulting in infinite loops or crashes.
- Integrity,Confidentiality,Availability: Execute Unauthorized Code or Commands: In some cases, integer coercion errors can lead to exploitable buffer overflow conditions, resulting in the execution of arbitrary code.
- Integrity,Other: Other: Integer coercion errors result in an incorrect value being stored for the variable in question.
Developer Pattern
CWE-192 is the kind of defect developers can usually prevent with explicit validation, safer framework defaults, and tests that exercise hostile input or unsafe state transitions.
Confidence
high confidence from CWE-192, 4.20.
Official CWE Definition
CWE-192: Integer Coercion Error
Integer coercion refers to a set of flaws pertaining to the type casting, extension, or truncation of primitive data types.
Several flaws fall under the category of integer coercion errors. For the most part, these errors in and of themselves result only in availability and data integrity issues. However, in some circumstances, they may result in other, more complicated security related flaws, such as buffer overflow conditions.
Developer And Remediation Guidance
How teams prevent and detect this weakness
Causes
- The following code is intended to read an incoming packet from a socket and extract one or more headers. The code performs a check to make sure that the packet does not contain too many headers. However, numHeaders is defined as a signed int, so it could be negative. If the incoming packet specifies a value such as -3, then the malloc calculation will generate a negative number (say, -300 if each header can be a maximum of 100 bytes). When this result is provided to malloc(), it is first converted to a size_t type. This conversion then produces a large value such as 4294966996, which may cause malloc() to fail or to allocate an extremely large amount of memory (CWE-195). With the appropriate negative numbers, an attacker could trick malloc() into using a very small positive number, which then allocates a buffer that is much smaller than expected, potentially leading to a buffer overflow.
- The following code reads a maximum size and performs validation on that size. It then performs a strncpy, assuming it will not exceed the boundaries of the array. While the use of "short s" is forced in this particular example, short int's are frequently used within real-world code, such as code that processes structured data. This code first exhibits an example of CWE-839, allowing "s" to be a negative number. When the negative short "s" is converted to an unsigned integer, it becomes an extremely large positive integer. When this converted integer is used by strncpy() it will lead to a buffer overflow (CWE-119).
Remediation
- Requirements: A language which throws exceptions on ambiguous data casts might be chosen.
- Architecture and Design: Design objects and program flow such that multiple or complex casts are unnecessary
- Implementation: Ensure that any data type casting that you must used is entirely understood in order to reduce the plausibility of error in use.
Detection
- Automated Static Analysis: 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.)
Mappings
Related CVEs, CWEs, and ATT&CK context
ATT&CK Relevance
ATT&CK relevance is shown only when reviewed or responsibly inferred.