Cross-source coverage

T1499.001 / ATT&CK

Endpoint Denial of Service: OS Exhaustion Flood

1 rule across 1 source.

From MITRE ATT&CK 19.2

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.

Tactics
Impact
Platforms
Linux · macOS · Windows
Telemetry
WinEventLog:SysmonWinEventLog:Microsoft-Windows-TCPIPNSM:Firewallauditd:SYSCALLNSM:Flowmacos:unifiedlogmacos:osquery

How MITRE says to detect it DET0356

Endpoint DoS via OS Exhaustion Flood Detection Strategy

Windows Analytic 1012

Burst of incomplete TCP handshakes (e.g., SYN floods) or uncorrelated ACK packets targeting the state table resulting in OS resource exhaustion.

  • WinEventLog:Sysmon EventCode=1
  • WinEventLog:Microsoft-Windows-TCPIP Connection queue overflow or failure to allocate TCP state object
  • NSM:Firewall High rate of inbound TCP SYN or ACK packets with missing 3-way handshake completion

Linux Analytic 1013

Flood of spoofed SYN or ACK packets causing exhaustion of OS TCP state table, potentially via user-space utilities or kernel-level DoS agents.

  • auditd:SYSCALL Invocation of packet generation tools (e.g., hping3, nping) or fork bombs
  • NSM:Flow High volumes of SYN/ACK packets with unacknowledged TCP handshakes
  • NSM:Flow TCP: possible SYN flood or backlog limit exceeded

macOS Analytic 1014

Adversary tool/script issuing mass SYN/ACK floods that degrade OS responsiveness and interrupt service response on macOS endpoints.

  • macos:unifiedlog network stack resource exhaustion, tcp_accept queue overflow, repeated resets
  • macos:osquery Execution of flooding tools or compiled packet generators
  • NSM:Firewall Anomalous TCP SYN or ACK spikes from specific source or interface

View on attack.mitre.org ↗

SigmaHQ/sigma

1 rule
Detection Severity Format
NTFS Vulnerability Exploitation High Sigma

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