CWE-463: Deletion of Data Structure Sentinel

Description

The accidental deletion of a data-structure sentinel can cause serious programming logic problems.

Often times data-structure sentinels are used to mark structure of the data structure. A common example of this is the null character at the end of strings. Another common example is linked lists which may contain a sentinel to mark the end of the list. It is dangerous to allow this type of control data to be easily accessible. Therefore, it is important to protect from the deletion or modification outside of some wrapper interface which provides safety.

Potential Impact

Availability, Other

Other

Authorization, Other

Other

Demonstrative Examples

This example creates a null terminated string and prints it contents.

Bad

char *foo;int counter;foo=calloc(sizeof(char)*10);
                     for (counter=0;counter!=10;counter++) {foo[counter]='a';
                     printf("%s\n",foo);}

The string foo has space for 9 characters and a null terminator, but 10 characters are written to it. As a result, the string foo is not null terminated and calling printf() on it will have unpredictable and possibly dangerous results.

Mitigations & Prevention

Architecture and Design

Use an abstraction library to abstract away risky APIs. Not a complete solution.

Build and Compilation Defense in Depth

Run or compile the software using features or extensions that automatically provide a protection mechanism that mitigates or eliminates buffer overflows. For example, certain compilers and extensions provide automatic buffer overflow detection mechanisms that are built into the compiled code. Examples include the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice.

Operation

Use OS-level preventative functionality. Not a complete solution.

Taxonomy Mappings

CLASP: — Deletion of data-structure sentinel

Frequently Asked Questions

What is CWE-463?

CWE-463 (Deletion of Data Structure Sentinel) is a software weakness identified by MITRE's Common Weakness Enumeration. It is classified as a Base-level weakness. The accidental deletion of a data-structure sentinel can cause serious programming logic problems.

How can CWE-463 be exploited?

Attackers can exploit CWE-463 (Deletion of Data Structure Sentinel) to other. This weakness is typically introduced during the Implementation phase of software development.

How do I prevent CWE-463?

Key mitigations include: Use an abstraction library to abstract away risky APIs. Not a complete solution.

What is the severity of CWE-463?

CWE-463 is classified as a Base-level weakness (Medium abstraction). Its actual severity depends on the specific context and how the weakness manifests in your application.