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Base · Medium

CWE-1325: Improperly Controlled Sequential Memory Allocation

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...

CWE-1325 · Base Level ·3 CVEs ·2 Mitigations

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.

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.

Potential Impact

Availability

DoS: Resource Consumption (Memory)

Demonstrative Examples

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
// 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.

Mitigations & Prevention

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.

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.

Real-World CVE Examples

CVE IDDescription
CVE-2020-36049JavaScript-based packet decoder uses concatenation of many small strings, causing out-of-memory (OOM) condition
CVE-2019-20176Product allocates a new buffer on the stack for each file in a directory, allowing stack exhaustion
CVE-2013-1591Chain: 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.

CWE-770: Allocation of Resources Without Limits or Throttling

The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended rest...

CWE-789: Memory Allocation with Excessive Size Value

The product allocates memory based on an untrusted, large size value, but it does not ensure that the size is within exp...

CWE-476: NULL Pointer Dereference

The product dereferences a pointer that it expects to be valid but is NULL.

Frequently Asked Questions

What is CWE-1325?

CWE-1325 (Improperly Controlled Sequential Memory Allocation) is a software weakness identified by MITRE's Common Weakness Enumeration. It is classified as a Base-level weakness. 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...

How can CWE-1325 be exploited?

Attackers can exploit CWE-1325 (Improperly Controlled Sequential Memory Allocation) to dos: resource consumption (memory). This weakness is typically introduced during the Implementation phase of software development.

How do I prevent CWE-1325?

Key mitigations include: 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

What is the severity of CWE-1325?

CWE-1325 is classified as a Base-level weakness (Medium abstraction). It has been observed in 3 real-world CVEs.