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CWE-130: Improper Handling of Length Parameter Inconsistency
 DescriptionDescription Summary The software parses a formatted message or structure, but it does not handle or incorrectly handles a length field that is inconsistent with the actual length of the associated data.
Extended Description If an attacker can manipulate the length parameter associated with an input such that it is inconsistent with the actual length of the input, this can be leveraged to cause the target application to behave in unexpected, and possibly, malicious ways. One of the possible motives for doing so is to pass in arbitrarily large input to the application. Another possible motivation is the modification of application state by including invalid data for subsequent properties of the application. Such weaknesses commonly lead to attacks such as buffer overflows and execution of arbitrary code. Alternate Terms
Time of Introduction
Applicable PlatformsLanguages C: (Sometimes) C++: (Sometimes) All Common Consequences
Demonstrative ExamplesExample 1 In the following C/C++ example the method processMessageFromSocket() will get a message from a socket, placed into a buffer, and will parse the contents of the buffer into a structure that contains the message length and the message body. A for loop is used to copy the message body into a local character string which will be passed to another method for processing. (Bad Code) Example Languages: C and C++ int processMessageFromSocket(int socket) { int success;
char buffer[BUFFER_SIZE];
char message[MESSAGE_SIZE];
// get message from socket and store into buffer
//Ignoring possibliity that buffer >
BUFFER_SIZE
if (getMessage(socket, buffer, BUFFER_SIZE) > 0)
{
// place contents of the buffer into message
structure
ExMessage *msg = recastBuffer(buffer);
// copy message body into string for
processing
int index;
for (index = 0; index < msg->msgLength;
index++) {
message[index] = msg->msgBody[index];
}
message[index] = '\0';
// process message
success = processMessage(message);
}
return success;
} However, the message length variable from the structure is used as the condition for ending the for loop without validating that the message length variable accurately reflects the length of message body. This can result in a buffer over read by reading from memory beyond the bounds of the buffer if the message length variable indicates a length that is longer than the size of a message body (CWE-130). Observed Examples
Potential Mitigations
Weakness Ordinalities
Relationships
Relationship Notes
Causal NatureImplicit Taxonomy Mappings
Related Attack Patterns
Content History
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Page Last Updated:
February 20, 2013
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