COMMON WEAKNESS ENUMERATIONDraft

CWE-400

Uncontrolled Resource Consumption

The product does not properly control the allocation and maintenance of a limited resource.

Abstraction

Class

Structure

Simple

Likelihood of Exploit

High

Understand the problem

What is the problem?

The product does not properly control the allocation and maintenance of a limited resource.

Terminology

Alternate terms and usages

Resource Exhaustion

Root cause

How and when does the problem arise?

Lifecycle phase

Operation

The product could be operated in a system or environment with lower resource limits than expected, which might make it easier for attackers to consume all available resources.

Lifecycle phase

System Configuration

The product could be configured with lower resource limits than expected, which might make it easier for attackers to consume all available resources.

Lifecycle phase

Architecture and Design

The designer might not consider how to handle and throttle excessive resource requests, which typically requires careful planning to handle more gracefully than a crash or exit.

Lifecycle phase

Implementation

There are at least three distinct scenarios that can commonly lead to resource exhaustion: - Lack of throttling for the number of allocated resources. - Losing all references to a resource before reaching the shutdown stage. - Not closing/returning a resource after processing. Resource exhaustion problems often occur due to an incorrect implementation of the following situations: - Error conditions and other exceptional circumstances. - Confusion over which part of the program is responsible for releasing the resource.

Risk

What does successful exploitation lead to?

DoS: Crash, Exit, or RestartDoS: Resource Consumption (CPU)DoS: Resource Consumption (Memory)DoS: Resource Consumption (Other)

Affected security scopes: Availability

If an attacker can trigger the allocation of the limited resources, but the number or size of the resources is not controlled, then the most common result is denial of service. This would prevent valid users from accessing the product, and it could potentially have an impact on the surrounding environment, i.e., the product may slow down, crash due to unhandled errors, or lock out legitimate users. For example, a memory exhaustion attack against an application could slow down the application as well as its host operating system.
Bypass Protection MechanismOther

Affected security scopes: Access Control, Other

In some cases it may be possible to force the product to "fail open" in the event of resource exhaustion. The state of the product -- and possibly the security functionality - may then be compromised.

Defence

How is it prevented and fixed?

Architecture and Design

Architecture and design approach

Detail
Design throttling mechanisms into the system architecture. The best protection is to limit the amount of resources that an unauthorized user can cause to be expended. A strong authentication and access control model will help prevent such attacks from occurring in the first place. The login application should be protected against DoS attacks as much as possible. Limiting the database access, perhaps by caching result sets, can help minimize the resources expended. To further limit the potential for a DoS attack, consider tracking the rate of requests received from users and blocking requests that exceed a defined rate threshold.

Architecture and Design

Architecture and design approach

Detail
Mitigation of resource exhaustion attacks requires that the target system either: - recognizes the attack and denies that user further access for a given amount of time, or - uniformly throttles all requests in order to make it more difficult to consume resources more quickly than they can again be freed. The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question. The second solution is simply difficult to effectively institute -- and even when properly done, it does not provide a full solution. It simply makes the attack require more resources on the part of the attacker.

Architecture and Design

Architecture and design approach

Detail
Ensure that protocols have specific limits of scale placed on them.

Implementation

Implementation-phase defence

Detail
Ensure that all failures in resource allocation place the system into a safe posture.

Verification

How is it detected?

Automated Static Analysis

Limited
Automated static analysis typically has limited utility in recognizing resource exhaustion problems, except for program-independent system resources such as files, sockets, and processes. For system resources, automated static analysis may be able to detect circumstances in which resources are not released after they have expired. Automated analysis of configuration files may be able to detect settings that do not specify a maximum value. Automated static analysis tools will not be appropriate for detecting exhaustion of custom resources, such as an intended security policy in which a bulletin board user is only allowed to make a limited number of posts per day.

Automated Dynamic Analysis

Moderate
Certain automated dynamic analysis techniques may be effective in spotting resource exhaustion problems, especially with resources such as processes, memory, and connections. The technique may involve generating a large number of requests to the product within a short time frame.

Fuzzing

Opportunistic
While fuzzing is typically geared toward finding low-level implementation bugs, it can inadvertently find resource exhaustion problems. This can occur when the fuzzer generates a large number of test cases but does not restart the targeted product in between test cases. If an individual test case produces a crash, but it does not do so reliably, then an inability to handle resource exhaustion may be the cause.

MITRE diagram

Weakness relationships and flow

CWE-400 MITRE diagramı
CWE-400: Common Weakness Enumeration Entry CWE-400 · DayBreach Sözlük · DayBreach