DLLHijackHunter

By ProjectMerai

Automated DLL Hijacking Discovery, Validation, and Confirmation
Turning local misconfigurations into weaponized, confirmed attack paths.

Overview

DLLHijackHunter is an automated Windows DLL hijacking detection tool that goes beyond static analysis. It discovers, validates, and confirms DLL hijacking opportunities using a multi-phase pipeline:

1. Discovery — Enumerates binaries across services, scheduled tasks, startup items, COM objects, and AutoElevate UAC bypass vectors
2. Filtration — Eliminates false positives through intelligent hard and soft gates
3. Canary Confirmation — Deploys a harmless canary DLL and triggers the binary to prove the hijack works
4. Scoring & Reporting — Ranks findings by exploitability with a tiered confidence system

Most DLL hijacking tools stop at “this DLL might be hijackable.” DLLHijackHunter attempts to validate it, cross-reference it against known exploit intelligence, and confirm real execution paths where possible.

Architecture

flowchart TB
    subgraph Phase1["Phase 1: Discovery"]
        SE["Static Engine<br/>Services, Tasks, Startup,<br/>COM, Run Keys"]
        AE["AutoElevate Engine<br/>Manifest + COM UAC Bypass"]
        PE["PE Analyzer<br/>Import Tables, Delay Loads,<br/>Manifests, Exports"]
        ETW["ETW Engine<br/>Real-time DLL Load<br/>Monitoring"]
        SO["Search Order<br/>Calculator"]
    end

    subgraph Phase2["Phase 2: Filter Pipeline"]
        direction LR
        HG["Hard Gates<br/>(Binary Kill)"]
        SG["Soft Gates<br/>(Confidence Adj.)"]
    end

    subgraph Phase3["Phase 3: Load Verification (--verify-load)"]
        LP["LoadProbe<br/>Child-process loader test<br/>Probe DLL placed &amp; removed"]
    end

    subgraph Phase4["Phase 4: Canary"]
        CB["Canary DLL Builder"]
        TE["Trigger Executor"]
        VF["Verification"]
    end

    subgraph Phase5["Phase 5: Output"]
        SC["Tiered Scorer"]
        RC["Console Report"]
        RJ["JSON Report"]
        RH["HTML Report"]
    end

    SE --> PE --> SO
    AE --> PE
    ETW --> SO
    SO --> Phase2
    HG --> SG
    Phase2 --> Phase3
    Phase3 --> Phase4
    CB --> TE --> VF
    Phase4 --> Phase5

Key Features

Hijack Type Coverage

IFEO Debugger entries are enumerated and the referenced binary is analyzed for DLL imports, but there is no dedicated IFEO/KnownDLL-bypass hijack type — those are not advertised as standalone detections.

UAC Bypass Discovery

DLLHijackHunter includes dedicated UAC bypass discovery:

• Manifest AutoElevate — Scans System32 and SysWOW64 for EXEs with <autoElevate>true</autoElevate> in embedded manifests
• COM AutoElevation — Scans HKLM\SOFTWARE\Classes\CLSID for COM objects with Elevation\Enabled=1
• Side-Load Simulation — For AutoElevate binaries that do not call SetDllDirectory or SetDefaultDllDirectories, simulates the “copy EXE to writable folder + drop DLL” attack path

Targeted Vulnerability Knowledge Base

• Targeted vulnerability mapping — Cross-references discovered imports against a bundled snapshot of the HijackLibs dataset (≈590 documented DLL entries spanning ≈700 vulnerable executables), embedded as Resources/hijacklibs.json. A match boosts confidence and links the finding to its HijackLibs reference page; the absence of a match means nothing. The dataset is data-driven — refresh it by re-downloading https://hijacklibs.net/api/hijacklibs.json over that resource (no code changes required). Dataset © the HijackLibs project and contributors.
• Automated PATH exploitation — Evaluates writable PATH folders and generates hijack candidates for a curated map of native Windows services known to search PATH for missing DLLs
• Expanded phantom DLL hunting — Searches for a library of high-value phantom DLL opportunities across multiple categories

Filter Pipeline

The pipeline reduces false positives through two stages:

Hard Gates

• API set schema filtering (api-ms-*, ext-ms-*)
• KnownDLL filtering
• Attacker-relative ACL writability validation — a path counts as writable only if an unprivileged principal (Users / Authenticated Users / Everyone, plus leak-proof sub-admin service accounts like LOCAL SERVICE/NETWORK SERVICE) has effective write rights. Crucially, this is computed independently of the token the tool runs under, so running elevated does not make System32/Program Files look writable. This is what makes elevated runs meaningful for LPE triage.

Soft Gates

• WinSxS manifest penalty
• Privilege delta analysis
• LoadLibraryEx mitigation checks
• Signature validation checks
• Graceful error-handling penalties

Canary Confirmation

Instead of guessing, DLLHijackHunter attempts to prove hijacks work:

sequenceDiagram
    participant H as DLLHijackHunter
    participant B as Canary DLL Builder
    participant T as Trigger Executor
    participant V as Victim Binary

    H->>B: Build canary DLL
    B->>B: Extract precompiled canary<br/>(or compile a proxy with MSVC)
    B-->>H: canary.dll + confirmation file path
    H->>H: Place DLL at hijack path
    H->>T: Trigger binary execution
    T->>V: Start service / run task / COM activate
    V->>V: Loads canary DLL
    V-->>H: Writes confirmation file<br/>PID, privilege, integrity level
    H->>H: Record: CONFIRMED
    H->>H: Cleanup canary DLL

The canary DLL:

• Ships precompiled for both x64 and x86, embedded in the scanner, so no compiler is required at scan time. The correct architecture is selected to match the victim's bitness and extracted on demand.
• Is self-locating: it derives its confirmation-file path at runtime from its own loaded module path (%ProgramData%\DLLHijackHunter\canary_<hash>.confirm), so one binary serves every candidate. The scanner computes the same hash from the deploy path and polls for that file.
• Uses a file-based confirmation mechanism
• Captures execution metadata such as user, integrity level, and privilege indicators
• Contains no malicious payload; it is strictly a detection and validation mechanism
• Statically links the CRT, so it has no runtime dependency (ucrtbase/vcruntime) on the victim host.

The bundled binaries are built from the auditable source at src/DLLHijackHunter/Resources/canary_src.c and can be regenerated with Resources/build_canary.bat (requires the MSVC C++ toolchain; the scanner does not).

Functional-proxy exception: When a search-order hijack targets a DLL that exists and exposes exports, keeping the host alive after confirmation requires an export-forwarding proxy, which is compiled per-DLL with MSVC (cl.exe, located via vswhere/vcvarsall). If no toolchain is present, the precompiled canary is used instead — it still confirms the load (DllMain fires) but does not forward exports, so the host process may crash after the confirmation is recorded. Phantom-DLL and other no-export candidates need no compiler at all.

Signing: The embedded canaries are unsigned. Code-signing them (so they load under stricter policies and are attributable) requires a signing certificate and is left as a release-time step for the maintainer.

Important note on proxy/export-forwarding mode

Proxy/export-forwarding canaries are experimental and best-effort. Some targets may fail to load correctly or may behave unexpectedly depending on:

• ordinal-only exports
• decorated export names
• calling convention mismatches
• loader/runtime assumptions in the target process

That means a failed proxy canary does not always mean the underlying hijack path is impossible.

Load-Order Verification (--verify-load)

An opt-in, standard-user verification that sits between the filter pipeline and canary phase. For each applicable candidate it briefly writes a benign probe DLL to the writable hijack position, then asks the real Windows loader — in a short-lived child process — to resolve the DLL by name. Where the loader resolves determines the verdict:

• Verified win — the loader picks the writable position. The search-order claim is proven (this corroboration lets the finding reach the High tier; canary execution remains the only path to Confirmed).
• Loses to protected — the loader picks a KnownDLL, the System32 copy, or a SxS-redirected copy instead. The position is almost certainly not hijackable, so the candidate is heavily demoted. This catches the classic false positives a static search-order calculator misses (e.g. a .local/search-order "finding" for ntdll.dll that KnownDLLs makes unexploitable).

Design and safety notes:

• Runs in a child process so a name already loaded into the scanner can't short-circuit the result, and so any load side effect or crash is isolated. No elevation required.
• Each probe is placed, resolved, and then removed; any pre-existing file is backed up and restored.
• It models the modern LOAD_LIBRARY_SEARCH ordering, so it is only applied to Phantom / Search-Order / Side-Load candidates. .local, PATH, and AppInit/AppCert candidates use different mechanics and are reported as Skipped.
• It writes files transiently to candidate positions (medium-impact); leave it off for fully passive, read-only triage.

# Standard-user triage with loader-verified search order (no canary, no ETW)
.\DLLHijackHunter.exe --lpe-only --no-canary --no-etw --verify-load

Comparison

Usage

Prerequisites

• Windows 10/11 or Windows Server 2016+
• .NET 8.0 or 10.0 Runtime (or use a self-contained build)
• Administrator privileges recommended (required for ETW, canary deployment, and some service triggers)

Build

git clone https://github.com/ghostvectoracademy/DLLHijackHunter.git
cd DLLHijackHunter

# Build (self-contained single file)
dotnet publish src/DLLHijackHunter/DLLHijackHunter.csproj `
    -c Release -r win-x64 --self-contained `
    -p:PublishSingleFile=true -o ./publish

# Or use the build script
.\build.ps1

Quick Start

# Full aggressive scan (recommended, requires admin)
.\DLLHijackHunter.exe --profile aggressive

# Safe scan (no file drops, no triggers)
.\DLLHijackHunter.exe --profile safe

# UAC bypass focused scan
.\DLLHijackHunter.exe --profile uac-bypass

# Target a specific binary
.\DLLHijackHunter.exe --target "C:\Program Files\MyApp\app.exe"

# Target by filename (partial match)
.\DLLHijackHunter.exe --target notepad.exe

# Confirmed findings only
.\DLLHijackHunter.exe --profile redteam --format json -o report.json

CLI Options

DLLHijackHunter — Automated DLL Hijacking Detection

Options:
  -p, --profile <profile>        Scan profile [default: aggressive]
                                   aggressive | strict | safe | redteam | uac-bypass
  -o, --output <path>            Output file path (auto-detects format)
  -f, --format <format>          Output format [default: console]
                                   console | json | html
  -t, --target <target>          Target specific binary, directory, or filename
      --min-confidence <value>   Minimum confidence threshold 0-100. When omitted, each
                                   profile's own threshold applies; passing this overrides it.
      --no-canary                Disable canary confirmation
      --no-etw                   Disable ETW runtime discovery
      --verify-load              Verify search order with the real loader (see below).
                                   Standard-user; transiently writes a benign probe.
      --confirmed-only           Only show canary-confirmed findings
      --lpe-only                 Strict LPE hunting: ignore System32/Program Files, show
                                   only standard-user-writable vulnerabilities
      --log-file <path>          Write a diagnostic scan log to file
  -v, --verbose                  Verbose output

Note: --min-confidence is only treated as an override when you explicitly pass it. Otherwise the selected profile's threshold is used (e.g. safe = 50%, strict = 80%).

Scan Profiles

Scoring

Each finding receives confidence and impact signals that are combined into a final prioritization tier.

Typical impact considerations include:

• privilege gained
• trigger reliability
• stealth
• reboot persistence

Confirmed canary execution should be treated as the strongest validation signal.

Tier gating: the High and Confirmed tiers are reserved for findings backed by a proof signal — a fired canary, an ETW runtime load observation, or a documented knowledge-base match. A purely static search-order match, however clean, is capped at the top of the Medium tier and annotated as Static-only so unverified heuristics never present as high-confidence.

Recommended triage configuration

Because writability is evaluated attacker-relative, both elevated and standard-user runs are meaningful:

• For LPE triage, the most trustworthy configuration is a standard-user run with --lpe-only (and --no-canary if a compiler isn't available) — every surviving finding is genuinely writable by an unprivileged principal.
• Elevated runs are required for ETW and canary confirmation, and are now safe from the historical "everything in System32 looks writable" inversion.

Safety

DLLHijackHunter is designed for defensive security research, lab validation, auditing, and red-team simulation in authorized environments.

Use it only on systems and networks you own or are explicitly authorized to assess.

Operational notes

• Canary mode writes test DLLs to candidate locations
• Some triggers may briefly start or stop services/tasks during validation
• Proxy/export-forwarding canaries may destabilize fragile targets
• Safe profile is the preferred mode for production triage when file drops and triggers are not acceptable

Output

DLLHijackHunter supports:

• console reporting
• JSON export
• HTML export

Recommended workflow:

1. run a broad scan
2. review high-confidence findings
3. use canary confirmation selectively on high-value paths
4. preserve JSON/HTML output for reporting and triage

License

MIT

Credits

Built by ProjectMerai.