Failure to deallocate data

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Overview

If memory is allocated and not freed the process could continue to consume more and more memory and eventually crash.

Consequences

  • Availability: If an attacker can find the memory leak, an attacker may be able to cause the application to leak quickly and therefore cause the application to crash.

Exposure period

  • Requirements specification: The choice could be made to use a language that is not susceptible to these issues.
  • Implementation: Many logic errors can lead to this condition. It can be exacerbated by lack of or misuse of mitigating technologies.

Platform

  • Languages: C, C++, Fortran, Assembly
  • Operating platforms: All, although partial preventative measures may be deployed depending on environment.

Required resources

Any

Severity

Medium

Likelihood of exploit

Medium

Avoidance and mitigation

  • Pre-design: Use a language or compiler that performs automatic bounds checking.
  • Design: Use an abstraction library to abstract away risky APIs. Not a complete solution.
  • Pre-design through Build: The Boehm-Demers-Weiser Garbage Collector or valgrind can be used to detect leaks in code. This is not a complete solution as it is not 100% effective.

Discussion

If a memory leak exists within a program, the longer a program runs, the more it encounters the leak scenario and the larger its memory footprint will become. An attacker could potentially discover that the leak locally or remotely can cause the leak condition rapidly so that the program crashes.

Examples

In C:

bar connection(){

 foo = malloc(1024);
 return foo;

} endConnection(bar foo){

 free(foo);

} int main() {

 while(1)
   //thread 1 
   //On a connection
   foo=connection();
   //thread 2
   //When the connection ends
   endConnection(foo)
 }

}

Here the problem is that every time a connection is made, more memory is allocated. So if one just opened up more and more connections, eventually the machine would run out of memory.

Related problems

Not available.

Categories