CWE-773: Missing Reference to Active File Descriptor or Handle
The product does not properly maintain references to a file descriptor or handle, which prevents that file descriptor/handle from being reclaimed.
How it's found
Missing Reference to Active File Descriptor or Handle is a specific, narrowly defined instance of a broader pattern. Testers confirm it with targeted code review and a proof-of-concept input that exercises the exact code path this weakness describes.
This can cause the product to consume all available file descriptors or handles, which can prevent other processes from performing critical file processing operations.
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-773?
The product does not properly maintain references to a file descriptor or handle, which prevents that file descriptor/handle from being reclaimed.
How do you find Missing Reference to Active File Descriptor or Handle?
Missing Reference to Active File Descriptor or Handle is a specific, narrowly defined instance of a broader pattern. Testers confirm it with targeted code review and a proof-of-concept input that exercises the exact code path this weakness describes.
What is the impact of CWE-773?
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 File Descriptor or Handle?
This weakness is not covered by the automated black-box pentest. IntegSec pentesters cover it in a manual engagement.
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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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