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Home > CWE List > CWE-704: Incorrect Type Conversion or Cast (4.18)
ID
CWE Glossary Definition

CWE-704: Incorrect Type Conversion or Cast

Weakness ID: 704
Vulnerability Mapping: ALLOWED This CWE ID could be used to map to real-world vulnerabilities in limited situations requiring careful review (with careful review of mapping notes)
Abstraction: Class Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.
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Description
The product does not correctly convert an object, resource, or structure from one type to a different type.
Common Consequences
Section HelpThis table specifies different individual consequences associated with the weakness. The Scope identifies the application security area that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in exploiting this weakness. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a weakness will be exploited to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.
Impact Details

Other

Scope: Other

Relationships
Section Help This table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
Relevant to the view "Research Concepts" (View-1000)
Nature Type ID Name
ChildOf Pillar Pillar - a weakness that is the most abstract type of weakness and represents a theme for all class/base/variant weaknesses related to it. A Pillar is different from a Category as a Pillar is still technically a type of weakness that describes a mistake, while a Category represents a common characteristic used to group related things. 664 Improper Control of a Resource Through its Lifetime
ParentOf Variant Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource. 588 Attempt to Access Child of a Non-structure Pointer
ParentOf Base Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource. 681 Incorrect Conversion between Numeric Types
ParentOf Base Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource. 843 Access of Resource Using Incompatible Type ('Type Confusion')
ParentOf Base Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource. 1389 Incorrect Parsing of Numbers with Different Radices
Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (View-1003)
Nature Type ID Name
MemberOf View View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries). 1003 Weaknesses for Simplified Mapping of Published Vulnerabilities
ParentOf Base Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource. 681 Incorrect Conversion between Numeric Types
ParentOf Base Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource. 843 Access of Resource Using Incompatible Type ('Type Confusion')
Modes Of Introduction
Section HelpThe different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.
Phase Note
Implementation
Applicable Platforms
Section HelpThis listing shows possible areas for which the given weakness could appear. These may be for specific named Languages, Operating Systems, Architectures, Paradigms, Technologies, or a class of such platforms. The platform is listed along with how frequently the given weakness appears for that instance.
Languages

C (Often Prevalent)

C++ (Often Prevalent)

Class: Not Language-Specific (Undetermined Prevalence)

Demonstrative Examples

Example 1


In this example, depending on the return value of accecssmainframe(), the variable amount can hold a negative value when it is returned. Because the function is declared to return an unsigned value, amount will be implicitly cast to an unsigned number.

(bad code)
Example Language: C
unsigned int readdata () {
int amount = 0;
...
amount = accessmainframe();
...
return amount;
}

If the return value of accessmainframe() is -1, then the return value of readdata() will be 4,294,967,295 on a system that uses 32-bit integers.



Example 2


The following code uses a union to support the representation of different types of messages. It formats messages differently, depending on their type.

(bad code)
Example Language: C
#define NAME_TYPE 1
#define ID_TYPE 2

struct MessageBuffer
{
int msgType;
union {
char *name;
int nameID;
};
};


int main (int argc, char **argv) {
struct MessageBuffer buf;
char *defaultMessage = "Hello World";

buf.msgType = NAME_TYPE;
buf.name = defaultMessage;
printf("Pointer of buf.name is %p\n", buf.name);
/* This particular value for nameID is used to make the code architecture-independent. If coming from untrusted input, it could be any value. */

buf.nameID = (int)(defaultMessage + 1);
printf("Pointer of buf.name is now %p\n", buf.name);
if (buf.msgType == NAME_TYPE) {
printf("Message: %s\n", buf.name);
}
else {
printf("Message: Use ID %d\n", buf.nameID);
}
}

The code intends to process the message as a NAME_TYPE, and sets the default message to "Hello World." However, since both buf.name and buf.nameID are part of the same union, they can act as aliases for the same memory location, depending on memory layout after compilation.

As a result, modification of buf.nameID - an int - can effectively modify the pointer that is stored in buf.name - a string.

Execution of the program might generate output such as:

Pointer of name is 10830
Pointer of name is now 10831
Message: ello World

Notice how the pointer for buf.name was changed, even though buf.name was not explicitly modified.

In this case, the first "H" character of the message is omitted. However, if an attacker is able to fully control the value of buf.nameID, then buf.name could contain an arbitrary pointer, leading to out-of-bounds reads or writes.



Selected Observed Examples

Note: this is a curated list of examples for users to understand the variety of ways in which this weakness can be introduced. It is not a complete list of all CVEs that are related to this CWE entry.

Reference Description
Chain: in a web browser, an unsigned 64-bit integer is forcibly cast to a 32-bit integer (CWE-681) and potentially leading to an integer overflow (CWE-190). If an integer overflow occurs, this can cause heap memory corruption (CWE-122)
Chain: data visualization program written in PHP uses the "!=" operator instead of the type-strict "!==" operator (CWE-480) when validating hash values, potentially leading to an incorrect type conversion (CWE-704)
Detection Methods
Method Details

Fuzzing
Fuzz testing (fuzzing) is a powerful technique for generating large numbers of diverse inputs - either randomly or algorithmically - and dynamically invoking the code with those inputs. Even with random inputs, it is often capable of generating unexpected results such as crashes, memory corruption, or resource consumption. Fuzzing effectively produces repeatable test cases that clearly indicate bugs, which helps developers to diagnose the issues.

Effectiveness: High
Memberships
Section HelpThis MemberOf Relationships table shows additional CWE Categories and Views that reference this weakness as a member. This information is often useful in understanding where a weakness fits within the context of external information sources.
Nature Type ID Name
MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 737 CERT C Secure Coding Standard (2008) Chapter 4 - Expressions (EXP)
MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 741 CERT C Secure Coding Standard (2008) Chapter 8 - Characters and Strings (STR)
MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 747 CERT C Secure Coding Standard (2008) Chapter 14 - Miscellaneous (MSC)
MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 875 CERT C++ Secure Coding Section 07 - Characters and Strings (STR)
MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 883 CERT C++ Secure Coding Section 49 - Miscellaneous (MSC)
MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 998 SFP Secondary Cluster: Glitch in Computation
MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 1129 CISQ Quality Measures (2016) - Reliability
MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 1157 SEI CERT C Coding Standard - Guidelines 03. Expressions (EXP)
MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 1158 SEI CERT C Coding Standard - Guidelines 04. Integers (INT)
MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 1161 SEI CERT C Coding Standard - Guidelines 07. Characters and Strings (STR)
MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 1306 CISQ Quality Measures - Reliability
MemberOf ViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries). 1340 CISQ Data Protection Measures
MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 1416 Comprehensive Categorization: Resource Lifecycle Management
Vulnerability Mapping Notes
Usage ALLOWED-WITH-REVIEW
(this CWE ID could be used to map to real-world vulnerabilities in limited situations requiring careful review)
Reason Abstraction

Rationale

This CWE entry is a Class and might have Base-level children that would be more appropriate

Comments

Examine children of this entry to see if there is a better fit
Taxonomy Mappings
Mapped Taxonomy Name Node ID Fit Mapped Node Name
CERT C Secure Coding EXP05-C Do not cast away a const qualification
CERT C Secure Coding EXP39-C CWE More Abstract Do not access a variable through a pointer of an incompatible type
CERT C Secure Coding INT31-C CWE More Abstract Ensure that integer conversions do not result in lost or misinterpreted data
CERT C Secure Coding INT36-C CWE More Abstract Converting a pointer to integer or integer to pointer
CERT C Secure Coding STR34-C CWE More Abstract Cast characters to unsigned types before converting to larger integer sizes
CERT C Secure Coding STR37-C CWE More Abstract Arguments to character handling functions must be representable as an unsigned char
Software Fault Patterns SFP1 Glitch in computation
OMG ASCRM ASCRM-CWE-704
References
[REF-961] Object Management Group (OMG). "Automated Source Code Reliability Measure (ASCRM)". ASCRM-CWE-704. 2016-01.
<http://www.omg.org/spec/ASCRM/1.0/>.
Content History
Submissions
Submission Date Submitter Organization
2008年09月09日
(CWE 1.0, 2008年09月09日) 		CWE Content Team MITRE
Note: this date reflects when the entry was first published. Draft versions of this entry were provided to members of the CWE community and modified between Draft 9 and 1.0.
Modifications
Modification Date Modifier Organization
2024年02月29日
(CWE 4.14, 2024年02月29日) 		CWE Content Team MITRE
updated Observed_Examples
2023年10月26日 CWE Content Team MITRE
updated Demonstrative_Examples, Observed_Examples
2023年06月29日 CWE Content Team MITRE
updated Mapping_Notes
2023年04月27日 CWE Content Team MITRE
updated Detection_Factors, Relationships, Time_of_Introduction
2023年01月31日 CWE Content Team MITRE
updated Description
2022年10月13日 CWE Content Team MITRE
updated Relationships
2020年12月10日 CWE Content Team MITRE
updated Relationships
2020年08月20日 CWE Content Team MITRE
updated Relationships
2020年02月24日 CWE Content Team MITRE
updated Relationships
2019年06月20日 CWE Content Team MITRE
updated Relationships
2019年01月03日 CWE Content Team MITRE
updated References, Relationships, Taxonomy_Mappings
2017年11月08日 CWE Content Team MITRE
updated Applicable_Platforms, Taxonomy_Mappings
2017年01月19日 CWE Content Team MITRE
updated Relationships
2015年12月07日 CWE Content Team MITRE
updated Relationships
2014年07月30日 CWE Content Team MITRE
updated Relationships, Taxonomy_Mappings
2012年05月11日 CWE Content Team MITRE
updated Relationships
2011年09月13日 CWE Content Team MITRE
updated Relationships, Taxonomy_Mappings
2011年06月01日 CWE Content Team MITRE
updated Common_Consequences, Relationships
2009年05月27日 CWE Content Team MITRE
updated Description
2008年11月24日 CWE Content Team MITRE
updated Relationships, Taxonomy_Mappings
2008年07月01日 Eric Dalci Cigital
updated Time_of_Introduction
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