T1055.001 — Dynamic-link Library Injection

T1055.001 Process Injection: Dynamic-link Library Injection

title: "T1055.001 Process Injection: Dynamic-link Library Injection"
id: 7bd4fe45-8984-443f-9243-10765edbdaeb
description: 'Detects ProcessAccess events where GrantedAccess grants memory read/write/operation and thread-creation rights (e.g. 0x1038, 0x103A) or near-full access (0x1F0FFF-0x1F3FFF), consistent with the VirtualAllocEx/WriteProcessMemory/CreateRemoteThread sequence used for DLL injection, with known AV/EDR/sysinternals tooling excluded. (Data Component: Process Access; baseline tier: windows-eventid.) Tune using: InjectedDLLSignatureStatus, TimeWindow, TargetProcessList, ParentProcessAnomalyThreshold.'
references:
  - https://attack.mitre.org/techniques/T1055/001
author: Shahrukh Khan
date: 2026-04-07
license: MIT
tags:
  - attack.stealth
  - attack.privilege-escalation
  - attack.t1055.001

logsource:
  product: windows
  service: sysmon

detection:
  selection:
    EventID: '10'
    GrantedAccess:
      - '0x1F0FFF'
      - '0x1F1FFF'
      - '0x1F2FFF'
      - '0x1F3FFF'
      - '0x1038'
      - '0x103A'
  filter_system_account:
    User|contains:
      - 'SYSTEM'
      - 'LOCAL SERVICE'
      - 'NETWORK SERVICE'
  filter_known_tools:
    SourceImage|endswith:
      - '\MsMpEng.exe'
      - '\ProcExp64.exe'
      - '\procexp.exe'
      - '\WmiPrvSE.exe'
      - '\vmtoolsd.exe'

  condition: selection and not (filter_system_account or filter_known_tools)

falsepositives:
  - AV/EDR engines, Sysinternals tools, and virtualization guest agents legitimately opening handles with these rights for scanning/telemetry (excluded via filter_known_tools); System and service accounts are excluded via filter_system_account; tune further with process/path allowlists if noise remains.

level: medium