type: attack-pattern
spec_version: 2.1
id: attack-pattern--0df05477-c572-4ed6-88a9-47c581f548f7
created: 2020-02-20T15:27:18.581Z
created_by_ref: identity--c78cb6e5-0c4b-4611-8297-d1b8b55e40b5
revoked: no
external_references: source_name: mitre-attack
url: https://attack.mitre.org/techniques/T1499/001
external_id: T1499.001
source_name: Cisco DoSdetectNetflow
description: Cisco. (n.d.). Detecting and Analyzing Network Threats With NetFlow. Retrieved April 25, 2019.
url: https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/netflow/configuration/15-mt/nf-15-mt-book/nf-detct-analy-thrts.pdf
source_name: Cloudflare SynFlood
description: Cloudflare. (n.d.). What is a SYN flood attack?. Retrieved April 22, 2019.
url: https://www.cloudflare.com/learning/ddos/syn-flood-ddos-attack/
source_name: Corero SYN-ACKflood
description: Corero. (n.d.). What is a SYN-ACK Flood Attack?. Retrieved November 17, 2024.
url: https://web.archive.org/web/20220119104451/https://www.corero.com/resource-hub/syn-ack-flood-attack/
source_name: Arbor AnnualDoSreport Jan 2018
description: Philippe Alcoy, Steinthor Bjarnason, Paul Bowen, C.F. Chui, Kirill Kasavchnko, and Gary Sockrider of Netscout Arbor. (2018, January). Insight into the Global Threat Landscape - Netscout Arbor's 13th Annual Worldwide Infrastructure Security Report. Retrieved April 22, 2019.
url: https://pages.arbornetworks.com/rs/082-KNA-087/images/13th_Worldwide_Infrastructure_Security_Report.pdf
object_marking_refs: marking-definition--fa42a846-8d90-4e51-bc29-71d5b4802168
modified: 2025-10-24T17:48:23.935Z
name: OS Exhaustion Flood
description: Adversaries may launch a denial of service (DoS) attack targeting an endpoint's operating system (OS). A system's OS is responsible for managing the finite resources as well as preventing the entire system from being overwhelmed by excessive demands on its capacity. These attacks do not need to exhaust the actual resources on a system; the attacks may simply exhaust the limits and available resources that an OS self-imposes.

Different ways to achieve this exist, including TCP state-exhaustion attacks such as SYN floods and ACK floods.(Citation: Arbor AnnualDoSreport Jan 2018) With SYN floods, excessive amounts of SYN packets are sent, but the 3-way TCP handshake is never completed. Because each OS has a maximum number of concurrent TCP connections that it will allow, this can quickly exhaust the ability of the system to receive new requests for TCP connections, thus preventing access to any TCP service provided by the server.(Citation: Cloudflare SynFlood)

ACK floods leverage the stateful nature of the TCP protocol. A flood of ACK packets are sent to the target. This forces the OS to search its state table for a related TCP connection that has already been established. Because the ACK packets are for connections that do not exist, the OS will have to search the entire state table to confirm that no match exists. When it is necessary to do this for a large flood of packets, the computational requirements can cause the server to become sluggish and/or unresponsive, due to the work it must do to eliminate the rogue ACK packets. This greatly reduces the resources available for providing the targeted service.(Citation: Corero SYN-ACKflood)
kill_chain_phases: kill_chain_name: mitre-attack
phase_name: impact
x_mitre_attack_spec_version: 3.2.0
x_mitre_deprecated: no
x_mitre_domains: enterprise-attack
x_mitre_is_subtechnique: yes
x_mitre_modified_by_ref: identity--c78cb6e5-0c4b-4611-8297-d1b8b55e40b5
x_mitre_platforms: Linux
macOS
Windows
x_mitre_version: 1.2
x_mitre_impact_type: Availability