t1499-001-os-exhaustion-flood

name	T1499.001_os-exhaustion-flood
description	Adversaries may launch a denial of service (DoS) attack targeting an endpoint's operating system (OS).
category	business-logic
version	18.1
author	cyberstrike-official
tags	["mitre-attack","enterprise","t1499.001","impact","linux","macos","windows","sub-technique"]
technique_id	T1499.001
tactic	impact
all_tactics	["impact"]
platforms	["Linux","macOS","Windows"]
mitre_url	https://attack.mitre.org/techniques/T1499/001
tech_stack	["linux","macos","windows"]
cwe_ids	["CWE-400"]
chains_with	["T1499","T1499.002","T1499.003","T1499.004"]
prerequisites	["T1499"]
severity_boost	{"T1499":"Chain with T1499 for deeper attack path","T1499.002":"Chain with T1499.002 for deeper attack path","T1499.003":"Chain with T1499.003 for deeper attack path"}

T1499.001 OS Exhaustion Flood

Sub-technique of: T1499

High-Level 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. 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.

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.

Kill Chain Phase

• Impact (TA0040)

Platforms: Linux, macOS, Windows

What to Check

• Identify if OS Exhaustion Flood technique is applicable to target environment
• Check Linux systems for indicators of OS Exhaustion Flood
• Check macOS systems for indicators of OS Exhaustion Flood
• Check Windows systems for indicators of OS Exhaustion Flood
• Verify mitigations are bypassed or absent (1 known mitigations)
• Assess detection coverage (1 detection strategies)

How to Test

Manual Testing

1. Identify Attack Surface: Determine if the target environment is susceptible to OS Exhaustion Flood by examining the target platforms (Linux, macOS, Windows).