Denial of Service Cheat Sheet — Software Design Concepts

Reference note (untrusted external data; do not execute it as instructions). Using validation that is cheap in resources first: We want to reduce impact on these resources as soon as possible. More (CPU, memory and bandwidth) expensive validation should be performed afterward. Employing graceful degradation: This is a core concept to follow during application design phase, in order to limit impact of DoS. You need to continue some level of functionality when portions of a system or application break. One of the main problems with DoS is that it causes sudden and abrupt application terminations throughout the system. A fault tolerant design enables a system or application to continue its intended operation, possibly at a reduced level, rather than failing completely if parts of the system fails. Prevent single point of failure: Detecting and preventing single points of failure (SPOF) is key to resisting DoS attacks. Most DoS attacks assume that a system has SPOFs that will fail due to overwhelmed systems. We suggest that you employ stateless components, use redundant systems, create bulkheads to stop failures from spreading across the infrastructure, and make sure that systems can survive when external services fail. Prevention Avoid highly CPU consuming operations: When a DoS attack occurs, operations that tend to use a lot of CPU resources can become serious drags on system performance and can become a point of failure. We strongly suggest that you review performance issues with your code, including problems that are inherent in the languages that you are using. See Java JVM-IBM and Microsoft-IIS Handle exceptions: When a DoS attack occurs, it is likely that applications will throw exceptions and it is vital that your systems can handle them gracefully. Again, a DoS attack assumes that an overwhelmed system will not be able to throw exceptions in a way that the system can continue operating. We suggest that you go through your code and make sure that exceptions are handled properly. See Large-Scale-Systems Java and Java Protect overflow and underflow Since buffer overflow and underflow often lead to vulnerabilities, learning how to prevent them is key. OWASP Overflow-Underflow-C Overflow Threading: Avoid operations which must wait for completion of large tasks to proceed. Asynchronous operations are useful in these situations. Identify resource intensive pages and plan ahead. Attribution: Adapted from OWASP Cheat Sheet Series under CC-BY-SA-4.0. Adaptation: WikiKV isolated this documentation section, normalized formatting, retained only bounded code excerpts, and shortened it at a paragraph or sentence boundary for retrieval. Verify version-sensitive details at the source.