CWE-771: Missing Reference to Active Allocated Resource
The product does not properly maintain a reference to a resource that has been allocated, which prevents the resource from being reclaimed.
How it's found
Missing Reference to Active Allocated Resource is typically found by tracing untrusted input from where it enters the system to the point where it is used without the check or neutralization this weakness describes, combining manual code review with dynamic testing.
This does not necessarily apply in languages or frameworks that automatically perform garbage collection, since the removal of all references may act as a signal that the resource is ready to be reclaimed.
Consequences
- DoS: Resource Consumption (Other): An attacker that can influence the allocation of resources that are not properly maintained could deplete the available resource pool and prevent all other processes from accessing the same type of resource.
Mitigations
- Operation/Architecture and Design: Use resource-limiting settings provided by the operating system or environment. For example, when managing system resources in POSIX, setrlimit() can be used to set limits for certain types of resources, and getrlimit() can determine how many resources are available. However, these functions are not available on all operating systems. When the current levels get close to the maximum that is defined for the application (see CWE-770), then limit the allocation of further resources to privileged users; alternately, begin releasing resources for less-privileged users. While this mitigation may protect the system from attack, it will not necessarily stop attackers from adversely impacting other users. Ensure that the application performs the appropriate error checks and error handling in case resources become unavailable (CWE-703).
Where this fits in a TurboPentest engagement
This weakness is not covered by the automated black-box pentest. IntegSec pentesters cover it in a manual engagement.
Frequently asked questions
What is CWE-771?
The product does not properly maintain a reference to a resource that has been allocated, which prevents the resource from being reclaimed.
How do you find Missing Reference to Active Allocated Resource?
Missing Reference to Active Allocated Resource is typically found by tracing untrusted input from where it enters the system to the point where it is used without the check or neutralization this weakness describes, combining manual code review with dynamic testing.
What is the impact of CWE-771?
DoS: Resource Consumption (Other): An attacker that can influence the allocation of resources that are not properly maintained could deplete the available resource pool and prevent all other processes from accessing the same type of resource.
Does TurboPentest test for Missing Reference to Active Allocated Resource?
This weakness is not covered by the automated black-box pentest. IntegSec pentesters cover it in a manual engagement.
Related CWEs
Written and reviewed by
Michel Chamberland - Founder & CEO, IntegSec
CISSP, OSCP, OSCE, CEH, GIAC, CCSK · 20+ years in offensive security
Michel has spent 20+ years on offensive security teams including IBM X-Force Red and Trustwave SpiderLabs, leading penetration tests, red team engagements, and breach response for Fortune 500 customers. He is the founder of IntegSec and the architect of TurboPentest.
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