FileInspectorX — Content Type Detection and Analysis for .NET and PowerShell

📦 NuGet (Library)

💻 PowerShell Module

🛠️ Project Information

👨‍💻 Author & Social

What it's all about

FileInspectorX is a library for content type detection (magic bytes + heuristics) and lightweight analysis (containers, PDFs, PE triage, text/script cues) across .NET 8, .NET Standard 2.0 and .NET Framework 4.7.2. A thin PowerShell module provides pipeline‑friendly cmdlets with reusable typed views.

Install

NuGet (Library)

dotnet add package FileInspectorX

PowerShell (Module)

Install-Module FileInspectorX.PowerShell
# or local build
Import-Module .\FileInspectorX.PowerShell\bin\Debug\net8.0\FileInspectorX.PowerShell.dll

C# Quick Start

using FileInspectorX;

var options = new FileInspector.DetectionOptions { ComputeSha256 = true, MagicHeaderBytes = 16 };
var analysis = FileInspector.Analyze(path, options);

Console.WriteLine($"{analysis.Detection?.Extension} {analysis.Detection?.MimeType} {analysis.Kind} {analysis.Flags}");

// Flatten for tabular/log display
var summary = SummaryView.From(path, analysis);
var perms   = PermissionsView.From(path, analysis.Security);
var sig     = SignatureView.From(path, analysis.Authenticode);

// Detection only
var detOnly = FileInspector.Detect(path, options);

PowerShell Examples

# Raw is default (full object)
Get-FileInsight -Path .\file.bin | Format-List

# Opt-in compact views
Get-FileInsight -Path .\file.bin -View Summary | Format-Table -Auto

# Other views: Summary | Detection | Permissions | Signature | Analysis
Get-FileInsight -Path .\file.bin -View Detection | Format-Table -Auto
Get-FileInsight -Path .\file.bin -View Permissions | Format-Table Path,Owner,Group,ModeSymbolic,EveryoneWriteAllowed -Auto
Get-FileInsight -Path .\app.exe -View Signature | Format-List
Get-FileInsight -Path .\package.msix -View Installer | Format-Table -Auto

# Exclude sections to trim work/shape
Get-FileInsight -Path .\file.bin -ExcludePermissions -ExcludeReferences | Format-List

# Back-compat: detection only
Get-FileInsight -Path .\file.bin -DetectOnly | Format-List

PowerShell quick help

# Discover parameters and examples
Get-Help Get-FileInsight -Detailed
Get-Help Get-FileInsight -Examples

# Detect-only for all EXE files under the current directory
Get-ChildItem -Filter *.exe -File -Recurse | Get-FileInsight -View Detection | Format-Table -Auto

# Summarize a directory, skipping signature and installer enrichment
Get-ChildItem -File -Recurse | Get-FileInsight -View Summary -ExcludeSignature -ExcludeInstaller | Format-Table -Auto

Views

• SummaryView: Path, Kind, Extension, MimeType, Confidence, Reason, Flags
• DetectionView: Path, Extension, MimeType, Confidence, Reason, ReasonDetails, BytesInspected, Sha256Hex, MagicHeaderHex
• AnalysisView: container/text/script/PE/Auth summaries
• PermissionsView (Windows & Unix): Owner/Group (+ IDs), ModeOctal/ModeSymbolic, IsExecutable, Everyone/Users/Admins read/write, HasDenyEntries
• SignatureView: Present, EnvelopeSignatureValid, ChainValid, Timestamp, signer info, FileHashMatches, SubjectCN/Org, IssuerCN/Org, IsSelfSigned
• InstallerView: Name/Publisher/Version/Manufacturer/ProductCode for MSI; Identity/Publisher/Display for MSIX/APPX; Publisher for VSIX
• ReferencesView: (generic) FilePath/Url/Command values found in configs (Task XML, scripts.ini), with Exists and Issues flags
• AssessmentView: compact risk score (0–100), decision (Allow/Warn/Block/Defer), and finding codes
  • Codes include: Package.VendorPresent/VendorUnknown/VendorAllowed, Sig.VendorAllowed/Sig.VendorUnknown, Archive.* and Pdf.* flags, etc.

Usage Model: Raw + Views + Exclude Toggles

• Default Raw

  • The cmdlet returns the full FileAnalysis object by default (-View Raw). This is a single, rich object with Detection, Flags, Security, Authenticode/Installer, References, Assessment, Secrets summary, and more.

• Views for display

  • Use -View Summary|Detection|Analysis|Permissions|Signature|References|Assessment|Installer to get compact, tabular shapes.
  • Every view carries .Raw so you can drill back into the full object without re‑invoking.

• Trim work/shape with excludes

  • -ExcludePermissions, -ExcludeSignature, -ExcludeInstaller, -ExcludeReferences, -ExcludeContainer, -ExcludeAssessment.
  • In C#, use new FileInspector.DetectionOptions { IncludePermissions = false, ... }.

API Choices: Detect vs Inspect vs Analyze

Pick the API based on how much work you want the library to do and how much metadata you need:

• Detect(path[, options]) → ContentTypeDetectionResult

  • Fast header-only magic/heuristics (null if unknown)
  • Minimal I/O, ideal for bulk triage or hot loops
  • options can still capture Sha256Hex and MagicHeaderHex

• Inspect(path[, options]) → FileAnalysis (single entry point)

  • If options.DetectOnly = true → returns a minimal FileAnalysis wrapping Detect
  • Otherwise → performs full analysis (same as Analyze)

• Analyze(path[, options]) → FileAnalysis

  • Full analysis: container/PDF/PE/Auth/permissions/script cues/CSV estimates
  • Returns everything Detect provides plus extra flags and metadata

Examples (C#)

// Detection only (fast)
var det = FileInspector.Detect(path, new FileInspector.DetectionOptions { MagicHeaderBytes = 16 });

// Single entry point (detect-only)
var detFa = FileInspector.Inspect(path, new FileInspector.DetectionOptions { DetectOnly = true });

// Full analysis
var full = FileInspector.Inspect(path, new FileInspector.DetectionOptions { ComputeSha256 = true });
var summary = full.ToSummaryView(path);

Features

• Fast detection: magic bytes + heuristics (images, archives, PDFs, executables, text/markup, scripts, CSV/TSV, DMG/ISO/UDF, EVTX, ESE, RIFF/media, etc.)
• Humanized output: friendly type labels (e.g., “Word document”, “ZIP archive”) and legend‑based flag descriptions via ReportView
• Analysis helpers
  • ZIP/TAR summaries (EntryCount, TopExtensions, nested archive hints)
  • Optional deep container scan (bounded): disguised types, known tool indicators, inner signers summary (see below)
  • PDF flags (JavaScript, OpenAction, AA, Names tree, EmbeddedFiles, ManyEmbeddedFiles)
  • PE triage (machine/subsystem, UPX hint)
  • Text family & CSV/TSV line estimates; generic log/schema cues (IIS W3C, Event XML, Sysmon, LDIF, AAD, MDE)
• Script safety cues (neutral): ps:encoded, ps:iex, py:exec-b64, lua:exec, rb:eval (no raw high‑signal strings)
• Secrets (privacy‑safe counts only): PrivateKey/JWT/KeyPattern
• Permissions snapshot: cross‑platform owner/group + Unix modes; Windows ACL summaries (Everyone/Users/Admins read/write, deny ACEs); MOTW/ADS on Windows
• Signatures: Authenticode summary and optional Windows policy (WinVerifyTrust) + timestamp/EKUs
• Crypto file detection:
  • ASCII‑armored PGP blocks (message/public key/signature)
  • Binary OpenPGP packet header (generic, low‑confidence)
  • DER X.509 certificate (heuristic ASN.1 OID scan)
  • PKCS#12/PFX (ASN.1 OID scan)
• Office & PDF flags:
  • OOXML (Word): Remote template (OfficeRemoteTemplate), possible DDE (OfficePossibleDde)
  • OOXML (Excel): External links (OfficeExternalLinks) and count (OfficeExternalLinksCount)
  • PDF: XFA (PdfHasXfa), Encrypted (PdfEncrypted), ManyIncrementalUpdates (PdfManyIncrementalUpdates)
• Citrix cues: ICA files and Receiver/Workspace configuration (XML)
• AOT‑friendly: safe for NativeAOT
• Name/path checks: BiDi controls, double extension, extension mismatch, suspicious whitespace
• Archive safety: traversal/absolute paths/symlinks flags from ZIP sampling

References & Recipes

The library can extract generic references from common configuration files so consumers can validate what will execute or be accessed. This is domain‑agnostic and useful for many scenarios (build pipelines, endpoint hygiene, or pre‑upload checks).

• Extracted kinds: FilePath, Url, Command, EnvVar, RegistryPath, Clsid.
• Current extractors:
  • Windows Task Scheduler Task XML: captures <Exec><Command>, <Arguments>, <WorkingDirectory> and <ClassId> (COM handler). Flags unquoted paths, UNC usage, relative paths.
  • GPO scripts INI (scripts.ini / psscripts.ini): captures nCmd and nParameters values, extracts paths and URLs.

PowerShell

# List references from a Task XML
Get-FileInsight -Path .\Task.xml -View References | Format-Table -Auto

# List references in a GPO scripts.ini
Get-FileInsight -Path .\scripts.ini -View References | Format-Table -Auto

C#

var a = FileInspector.Analyze(path);
foreach (var r in a.References ?? Array.Empty<Reference>())
{
    Console.WriteLine($"{r.Kind} {r.Value} exists={r.Exists} issues={r.Issues}");
}

C# (Assessment)

var full = FileInspector.Analyze(path);
var assess = FileInspector.Assess(full);
Console.WriteLine($"Score={assess.Score} Decision={assess.Decision} Codes={string.Join(" ", assess.Codes)}");

// Factors show score contributions per code (explainability)
foreach (var kv in assess.Factors)
{
    Console.WriteLine($"{kv.Key} => {kv.Value}");
}

PowerShell (Assessment)

Get-FileInsight -Path .\file.bin -View Assessment | Format-Table -Auto

This stays generic by design. A higher‑level component (e.g., TierBridge) can layer policy (allow/warn/block) using these references and the existing Flags/SecurityFindings.

Inner Signers Inside Archives (deep scan)

When Settings.DeepContainerScanEnabled = true, FileInspectorX can sample a bounded number of inner executables in ZIP archives to provide a quick signer summary without fully extracting archives. The following fields are exposed on FileAnalysis and surfaced via ReportView:

• InnerExecutablesSampled: how many inner EXE/DLLs were sampled (bounded by DeepContainerMaxEntries and DeepContainerMaxEntryBytes).
• InnerSignedExecutables: how many of those were Authenticode‑signed.
• InnerValidSignedExecutables: how many had a valid chain or passed WinVerifyTrust (when available).
• InnerPublisherCounts: top publishers (SignerSubjectCN) with counts.

Notes:

• This is a best‑effort, privacy‑safe summary for triage. It extracts only sampled entries to a temporary file for analysis and deletes them immediately.
• Currently implemented for ZIP. TAR/7z/RAR can be added similarly if needed.

var a = FileInspector.Analyze(path);
if (a.InnerExecutablesSampled > 0)
{
    Console.WriteLine($"Inner execs: {a.InnerExecutablesSampled}, signed: {a.InnerSignedExecutables}, valid: {a.InnerValidSignedExecutables}");
    if (a.InnerPublisherCounts != null)
        foreach (var kv in a.InnerPublisherCounts.OrderByDescending(kv => kv.Value).Take(5))
            Console.WriteLine($"  {kv.Key}: {kv.Value}");
}

Friendly Type Labels & ReportView

Use ReportView.From(FileAnalysis) for presentation‑ready fields:

• DetectedTypeFriendly: a human‑friendly label (e.g., “Word document”, “ZIP archive”, “X.509 certificate”).
• FlagsHumanShort/Long: legend‑based humanization of flags and heuristics.
• AssessmentCodesHuman: humanized assessment codes.

These are exported via ReportView.ToDictionary() for templating/email systems.

Settings Cheatsheet

// Deep container scanning (bounded)
Settings.DeepContainerScanEnabled = true;      // default: false
Settings.DeepContainerMaxEntries = 64;         // sample cap
Settings.DeepContainerMaxEntryBytes = 262144;  // per‑entry cap (256 KB)

// Script & secrets scanning
Settings.SecurityScanScripts = true;           // default: true
Settings.SecretsScanEnabled = true;            // default: true

// Authenticode (Windows policy optional)
Settings.VerifyAuthenticodeWithWinTrust = true;   // default true on Windows
Settings.VerifyAuthenticodeRevocation = false;    // default

// Vendor allow hints (for assessment)
Settings.AllowedVendors = new[] { "Microsoft", "YourCompany" };
Settings.VendorMatchMode = VendorMatchMode.Contains; // or Exact

Flags → Assessment Codes (Quick Map)

• Archive safety

  • ArchiveHasPathTraversal → Archive.PathTraversal (+40)
  • ArchiveHasAbsolutePaths → Archive.AbsolutePath (+15)
  • ArchiveHasSymlinks → Archive.Symlink (+20)
  • ContainerContainsExecutables → Archive.ContainsExecutables (+25)
  • ContainerContainsScripts → Archive.ContainsScripts (+20)
  • ContainerContainsArchives → Archive.ContainsArchives (+15)

• Office / OOXML

  • HasOoxmlMacros → Office.Macros (+30)
  • OfficeRemoteTemplate → Office.RemoteTemplate (+25)
  • OfficePossibleDde → Office.PossibleDde (+15)
  • OfficeExternalLinks → Office.ExternalLinks (+5) [count exposed as OfficeExternalLinksCount]

• PDF

  • PdfHasJavaScript → Pdf.JavaScript (+20)
  • PdfHasOpenAction → Pdf.OpenAction (+15)
  • PdfHasLaunch → Pdf.Launch (+20)
  • PdfHasNamesTree → Pdf.NamesTree (+10)
  • PdfHasXfa → Pdf.Xfa (+10)
  • PdfEncrypted → Pdf.Encrypted (+10)
  • PdfManyIncrementalUpdates → Pdf.ManyUpdates (+5)

• PE hardening

  • PeLooksPackedUpx → PE.PackerSuspect (+20)
  • PeNoAslr → PE.NoASLR (+15)
  • PeNoNx → PE.NoNX (+20)
  • PeNoCfg → PE.NoCFG (+15)
  • PeNoHighEntropyVa (x64) → PE.NoHighEntropyVA (+5)

• Signatures

  • Self‑signed → Sig.SelfSigned (+20)
  • Chain invalid → Sig.ChainInvalid (+25)
  • Bad envelope → Sig.BadEnvelope (+15)
  • Vendor allowed (allowed list) → Sig.VendorAllowed (−10)

• Vendor / Package

  • Vendor present → Package.VendorPresent (0)
  • Vendor allowed (allowed list) → Package.VendorAllowed (−15)
  • Vendor unknown → Package.VendorUnknown (0)
  • MSI CustomActions (EXE/Script/DLL) → Msi.CustomActionExe (+20) / Msi.CustomActionScript (+20) / Msi.CustomActionDll (+10)

• Scripts & secrets (neutral categories)

  • Script.Encoded (+25), Script.IEX (+20), Script.WebDownload (+15), Script.Reflection (+10)
  • Secret.PrivateKey (+40), Secret.JWT (+25), Secret.KeyPattern (+15)

Assessment Pipeline (Flowchart)

flowchart TD
    A["Input path(s)"] --> B{"Detect (magic + heuristics)"}
    B -->|known| C["ContentTypeDetectionResult"]
    B -->|unknown| C

    C --> D{"Analyze (Include* flags)"}
    D --> D1["Container triage (ZIP/TAR subtype, safety, nested)"]
    D --> D2["Text/Script heuristics + Secrets"]
    D --> D3["Permissions / Ownership"]
    D --> D4["Signatures + Installer metadata"]
    D --> D5["PDF / OOXML flags"]
    D --> D6["Name / Path analysis"]
    D --> E["FileAnalysis"]

    E --> F{"IncludeAssessment?"}
    F -->|Yes| G["Assess() Score + Codes + Factors"]
    F -->|No| H["Return FileAnalysis"]

    G --> I["Decision: Allow / Warn / Block"]
    I --> J[["Views (optional)"]]
    H --> J

    subgraph Toggles
      T1["IncludeContainer"]
      T2["IncludePermissions"]
      T3["IncludeAuthenticode"]
      T4["IncludeInstaller"]
      T5["IncludeReferences"]
      T6["IncludeAssessment"]
    end

    T1 -.-> D1
    T2 -.-> D3
    T3 -.-> D4
    T4 -.-> D4
    T5 -.-> D2
    T6 -.-> G

Loading

Scoring Breakdown (Example)

pie showData
    title Example Score Composition
    "Archive.PathTraversal (+40)" : 40
    "Office.RemoteTemplate (+25)" : 25
    "Secret.PrivateKey (+40)" : 40
    "Sig.VendorAllowed (−10)" : 10

Loading

Notes

• Factors in Assessment.Factors report the exact weights (negative values reduce Score).
• Actual weights are configurable in code and may evolve; see README map above for typical values.

Sample Scenario Scores (Illustrative)

GitHub's Mermaid version may not support the new chart directive yet, so here's a pie fallback and a simple table.

pie showData
    title Scenario Scores (Illustrative)
    "Plain PDF (0)" : 0
    "PDF + JS (20)" : 20
    "DOCX + Macros (30)" : 30
    "DOCX + RemoteTpl (55)" : 55
    "ZIP with Executable (25)" : 25
    "MSI + CustomAction (50)" : 50

Loading

Scenario                  Score
------------------------  -----
Plain PDF                 0
PDF + JS                  20
DOCX + Macros             30
DOCX + Remote Template    55
ZIP with Executable       25
MSI with Custom Action    50

These values are illustrative only — actual scores depend on which signals are present and the configured weights.

Settings

• HeaderReadBytes (default 4096)
• DetectionReadBudgetBytes (default 1 MB)
• SecurityScanScripts (default true)
• VerifyAuthenticodeWithWinTrust (default true on Windows)
• VerifyAuthenticodeRevocation (default false)
• JS minified heuristics: JsMinifiedMinLength, JsMinifiedAvgLineThreshold, JsMinifiedDensityThreshold
• Assessment thresholds: AssessmentWarnThreshold, AssessmentBlockThreshold
• Vendor allow‑list: AllowedVendors (string[]), VendorMatchMode (Contains|Exact)
• Secrets: SecretsScanEnabled (default true)

Secrets Summary (privacy‑safe)

The full object (Raw/FileAnalysis) exposes Secrets with category counts only — no values are stored:

$fa = Get-FileInsight -Path .\script.ps1
$fa.Secrets | Format-List

var fa = FileInspector.Analyze(path);
var s = fa.Secrets;
Console.WriteLine($"privKeys={s?.PrivateKeyCount} jwt={s?.JwtLikeCount} keyPat={s?.KeyPatternCount}");

Signatures (Authenticode)

• Cross‑platform
  • Parses Authenticode PKCS#7 and extracts the content digest (SpcIndirectDataContent)
  • Recomputes PE image digest excluding checksum and WIN_CERTIFICATE table
  • Sets AuthenticodeInfo.FileHashMatches and FileDigestAlgorithm
• Windows (optional)
  • WinVerifyTrust policy verification (catalog-aware) → IsTrustedWindowsPolicy + WinTrustStatusCode

Permissions & Ownership

• Unix: mode bits via .NET (UnixFileMode); owner/group names via stat where available
• Windows: Owner/Group friendly names (NTAccount), ACL summaries
  • EveryoneReadAllowed/EveryoneWriteAllowed
  • BuiltinUsersReadAllowed/BuiltinUsersWriteAllowed
  • AdministratorsReadAllowed/AdministratorsWriteAllowed
  • HasDenyEntries

Platforms & AOT

• .NET 8, .NET Standard 2.0, .NET Framework 4.7.2
• NativeAOT friendly; WinVerifyTrust runs only on Windows

Build

• Library: dotnet build FileInspectorX/FileInspectorX.csproj
• Tests: dotnet test
• PowerShell module: dotnet build FileInspectorX.PowerShell (then Import-Module the built DLL)

Notes

• Script “security findings” are neutral codes — reduces AV triggers
• Owner/group on Unix via stat when available (fields may be null; mode bits still populate)