CWE

Common Weakness Enumeration

A Community-Developed List of Software & Hardware Weakness Types

CWE Top 25 Most Dangerous Weaknesses
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ID

CWE-1325: Improperly Controlled Sequential Memory Allocation

Weakness ID: 1325
Abstraction: Base
Structure: Simple
Status: Incomplete
Presentation Filter:
+ Description
The product manages a group of objects or resources and performs a separate memory allocation for each object, but it does not properly limit the total amount of memory that is consumed by all of the combined objects.
+ Extended Description

While the product might limit the amount of memory that is allocated in a single operation for a single object (such as a malloc of an array), if an attacker can cause multiple objects to be allocated in separate operations, then this might cause higher total memory consumption than the developer intended, leading to a denial of service.

+ Alternate Terms
Stack Exhaustion:
When a weakness allocates excessive memory on the stack, it is often described as "stack exhaustion," which is a technical impact of the weakness. This technical impact is often encountered as a consequence of CWE-789 and/or CWE-1325.
+ Relationships

The table(s) below shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.

+ Relevant to the view "Research Concepts" (CWE-1000)
NatureTypeIDName
ChildOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.770Allocation of Resources Without Limits or Throttling
PeerOfVariantVariant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.789Memory Allocation with Excessive Size Value
CanPrecedeBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.476NULL Pointer Dereference
+ Modes Of Introduction

The different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.

PhaseNote
Implementation
+ Applicable Platforms
The listings below show possible areas for which the given weakness could appear. These may be for specific named Languages, Operating Systems, Architectures, Paradigms, Technologies, or a class of such platforms. The platform is listed along with how frequently the given weakness appears for that instance.

Languages

C (Undetermined Prevalence)

C++ (Undetermined Prevalence)

Class: Language-Independent (Undetermined Prevalence)

+ Common Consequences

The table below specifies different individual consequences associated with the weakness. The Scope identifies the application security area that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in exploiting this weakness. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a weakness will be exploited to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.

ScopeImpactLikelihood
Availability

Technical Impact: DoS: Resource Consumption (Memory)

Not controlling memory allocation can result in a request for too much system memory, possibly leading to a crash of the application due to out-of-memory conditions, or the consumption of a large amount of memory on the system.
+ Demonstrative Examples

Example 1

This example contains a small allocation of stack memory. When the program was first constructed, the number of times this memory was allocated was probably inconsequential and presented no problem. Over time, as the number of objects in the database grow, the number of allocations will grow - eventually consuming the available stack, i.e. "stack exhaustion." An attacker who is able to add elements to the database could cause stack exhaustion more rapidly than assumed by the developer.

(bad code)
Example Language:
// Gets the size from the number of objects in a database, which over time can conceivably get very large
int end_limit = get_nmbr_obj_from_db();
int i;
int *base = NULL;
int *p =base;
for (i = 0; i < end_limit; i++)
{
*p = alloca(sizeof(int *)); // Allocate memory on the stack
p = *p; // // Point to the next location to be saved
}

Since this uses alloca(), it allocates memory directly on the stack. If end_limit is large enough, then the stack can be entirely consumed.

+ Observed Examples
ReferenceDescription
Product allocates a new buffer on the stack for each file in a directory, allowing stack exhaustion
Chain: an integer overflow (CWE-190) in the image size calculation causes an infinite loop (CWE-835) which sequentially allocates buffers without limits (CWE-1325) until the stack is full.
+ Potential Mitigations

Phase: Implementation

Ensure multiple allocations of the same kind of object are properly tracked - possibly across multiple sessions, requests, or messages. Define an appropriate strategy for handling requests that exceed the limit, and consider supporting a configuration option so that the administrator can extend the amount of memory to be used if necessary.

Phase: Operation

Run the program using system-provided resource limits for memory. This might still cause the program to crash or exit, but the impact to the rest of the system will be minimized.
+ Weakness Ordinalities
OrdinalityDescription
Primary
(where the weakness exists independent of other weaknesses)
+ Content History
+ Submissions
Submission DateSubmitterOrganization
2020-12-07CWE Content TeamMITRE
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Page Last Updated: December 10, 2020