CWE-770: Allocation of Resources Without Limits or Throttling

Causes

• This code allocates a socket and forks each time it receives a new connection. The program does not track how many connections have been made, and it does not limit the number of connections. Because forking is a relatively expensive operation, an attacker would be able to cause the system to run out of CPU, processes, or memory by making a large number of connections. Alternatively, an attacker could consume all available connections, preventing others from accessing the system remotely.
• In the following example a server socket connection is used to accept a request to store data on the local file system using a specified filename. The method openSocketConnection establishes a server socket to accept requests from a client. When a client establishes a connection to this service the getNextMessage method is first used to retrieve from the socket the name of the file to store the data, the openFileToWrite method will validate the filename and open a file to write to on the local file system. The getNextMessage is then used within a while loop to continuously read data from the socket and output the data to the file until there is no longer any data from the socket. This example creates a situation where data can be dumped to a file on the local file system without any limits on the size of the file. This could potentially exhaust file or disk resources and/or limit other clients' ability to access the service.
• In the following example, the processMessage method receives a two dimensional character array containing the message to be processed. The two-dimensional character array contains the length of the message in the first character array and the message body in the second character array. The getMessageLength method retrieves the integer value of the length from the first character array. After validating that the message length is greater than zero, the body character array pointer points to the start of the second character array of the two-dimensional character array and memory is allocated for the new body character array. This example creates a situation where the length of the body character array can be very large and will consume excessive memory, exhausting system resources. This can be avoided by restricting the length of the second character array with a maximum length check,Also, consider changing the type from 'int' to 'unsigned int', so that you are always guaranteed that the number is positive. This might not be possible if the protocol specifically requires allowing negative values, or if you cannot control the return value from getMessageLength(), but it could simplify the check to ensure the input is positive, and eliminate other errors such as signed-to-unsigned conversion errors (CWE-195) that may occur elsewhere in the code.
• In the following example, a server object creates a server socket and accepts client connections to the socket. For every client connection to the socket a separate thread object is generated using the ClientSocketThread class that handles request made by the client through the socket. In this example there is no limit to the number of client connections and client threads that are created. Allowing an unlimited number of client connections and threads could potentially overwhelm the system and system resources.,The server should limit the number of client connections and the client threads that are created. This can be easily done by creating a thread pool object that limits the number of threads that are generated.
• An unnamed web site allowed a user to purchase tickets for an event. A menu option allowed the user to purchase up to 10 tickets, but the back end did not restrict the actual number of tickets that could be purchased.
• Here the problem is that every time a connection is made, more memory is allocated. So if one just opened up more and more connections, eventually the machine would run out of memory.

Remediation

• Requirements: Clearly specify the minimum and maximum expectations for capabilities, and dictate which behaviors are acceptable when resource allocation reaches limits.
• Architecture and Design: Limit the amount of resources that are accessible to unprivileged users. Set per-user limits for resources. Allow the system administrator to define these limits. Be careful to avoid CWE-410.
• Architecture and Design: 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, and it will help the administrator to identify who is committing the abuse. 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.
• Implementation: [object Object]
• Architecture and Design: For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
• Architecture and Design: [object Object]
• Architecture and Design: Ensure that protocols have specific limits of scale placed on them.
• Architecture and Design,Implementation: [object Object]

Detection

• Manual Static Analysis: Manual static analysis can be useful for finding this weakness, but it might not achieve desired code coverage within limited time constraints. If denial-of-service is not considered a significant risk, or if there is strong emphasis on consequences such as code execution, then manual analysis may not focus on this weakness at all.
• Fuzzing: [object Object]
• Automated Dynamic Analysis: Certain automated dynamic analysis techniques may be effective in producing side effects of uncontrolled resource allocation 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. Manual analysis is likely required to interpret the results.
• Automated Static Analysis: [object Object]

Related CWEs

• CWE-1325: Improperly Controlled Sequential Memory Allocation
• CWE-20: Improper Input Validation
• CWE-400: Uncontrolled Resource Consumption
• CWE-400: Uncontrolled Resource Consumption
• CWE-665: Improper Initialization
• CWE-774: Allocation of File Descriptors or Handles Without Limits or Throttling
• CWE-789: Memory Allocation with Excessive Size Value

Related CVEs

Related CVE mappings appear after CVE records are cross-indexed.

ATT&CK Relevance

ATT&CK relevance is shown only when reviewed or responsibly inferred.