Malware – Baker Street Forensics

Streamline Malware Hash Search with FOSSOR

DFIR, Forensics, hashing, Malware, Python

We’ve all encountered this scenario: you’re reading a threat report from CISA or Microsoft and come across hashes related to a malware infection. You start copying these hashes and head to one of your favorite virus repositories to check if there’s a source available for download so you can analyze the malware yourself. Unfortunately, you don’t find a match. So, you move on to another site and repeat the process. This can be time-consuming and prone to errors.

FOSSOR (Federated Open-Source Sample Search & Object Retriever) is a script designed to help you search for malware hashes across multiple threat intelligence sources. Simply run FOSSOR and provide it with a single hash or a text file of hashes (.txt or .csv). It will instantly display which sources have information about the hash, and you can even download samples if needed.

Setup

FOSSOR loads API keys from text files in the same directory as the script. Create one file per source containing only the key:

Source	Key file	Where to get a key
MalwareBazaar	`mb-api.txt`	abuse.ch Auth Portal
VirusTotal	`vt-api.txt`	VirusTotal API
AlienVault OTX	`otx-api.txt`	OTX Account Settings

Sources with missing key files are automatically skipped. You only need the sources you have access to.

			
fossor/
  fossor.py
  mb-api.txt      # your MalwareBazaar key
  vt-api.txt      # your VirusTotal key
  otx-api.txt     # your OTX key
  samples/        # created automatically by --download

		

Usage

Look up hashes from a file

python3 fossor.py hashes.txt

The input file should have one hash per line. Lines starting with # are treated as comments and ignored. Works with .txt, .csv, or any text file — BOM and stray whitespace are handled automatically.

Look up a single hash

			
python3 fossor.py d0a2035c0431796c138a26d1c9a75142b613c5417dc96a9200723870d0b3a687

Export results to CSV

python3 fossor.py hashes.txt --csv results.csv

Download available samples

python3 fossor.py hashes.txt --download

Downloads are saved to ./samples/ as password-protected zips. The password is always infected.

Warning: Downloaded samples are live malware. Handle with appropriate caution — use a VM or isolated analysis environment. Consider excluding the samples/ directory from antivirus real-time scanning and Spotlight indexing.

Disable specific sources

			
python3 fossor.py hashes.txt --no-vt           # skip VirusTotal
python3 fossor.py hashes.txt --no-mb --no-otx  # only query VirusTotal

Combine options

python3 fossor.py hashes.txt --csv results.csv --download --no-vt

Example Output

			
[*] MalwareBazaar: key loaded
[*] VirusTotal: key loaded
[*] OTX: key loaded
[*] Querying 9 hashes (SHA256) across: MalwareBazaar, VirusTotal, OTX
[1/9] 9d867ddb54f37592fa0b... (SHA256)
  MalwareBazaar:    NOT FOUND
  VirusTotal:       HIT - trojan.fzdtv/fkmsvcr | ZIP | 22/76
  OTX:              HIT - Infostealers without borders... | FileHash-SHA256 | 3 pulses
[2/9] d0a2035c0431796c138a... (SHA256)
  MalwareBazaar:    HIT - RedLineStealer | exe
  VirusTotal:       HIT - trojan.laplasclipper/steal | Win32 EXE | 40/75
  OTX:              HIT - InfoStealers - Jan 2025 | FileHash-SHA256 | 1 pulses
============================================================
Summary: 9 hashes queried across 3 sources
  MalwareBazaar:    1/9 found
  VirusTotal:       6/9 found
  OTX:              5/9 found
  Unique hashes with at least one hit: 7/9
Results Matrix:
  Hash               Malwar     VT    OTX
  ------------------ ------ ------ ------
  9d867ddb54f37592fa      -    HIT    HIT
  08a1f4566657a07688      -    HIT      -
  5970d564b5b2f5a472      -    HIT    HIT
  d0a2035c0431796c13    HIT    HIT    HIT
  59855f0ec42546ce2b      -      -      -
  a5b19195f61925ede7      -    HIT    HIT
  e7237b233fc6fda614      -    HIT      -
  59347a8b1841d33afd      -      -    HIT
  e965eb96df16eac926      -      -      -
============================================================

		

Rate Limits

Source	Limit	FOSSOR default
MalwareBazaar	None documented	No delay
VirusTotal (free)	4 requests/min	15s between requests
AlienVault OTX	10,000 requests/hr	No delay

Download

You can download FOSSOR for free on GitHub: https://github.com/dwmetz/FOSSOR/

Enhancing Malware Analysis with REMnux and AI

DFIR, Forensics, Malware, REMnux

Those familiar with my work know that I’m a big fan of the REMnux Linux distribution for malware analysis. When I developed MalChela, I included a custom configuration that can be invoked that not only includes the MalChela tool suite but also integrates many of the CLI tools installed in REMnux, providing an easy-to-use GUI.

Recently, a new REMnux release was released on Ubuntu 24.04. This was a welcome upgrade because REMnux was previously locked to 20.04, which was becoming outdated. As soon as I noticed the release announcement, I downloaded the latest version and installed the MalChela suite. Everything ran smoothly, and the GUI interface even appeared slightly sharper without any changes on my part.

While reviewing the release notes for the new version, I discovered that REMnux now includes integration with Opencode AI. In REMnux, several models are preconfigured to recognize the tools included in the distribution and their capabilities and syntax. You can use natural language prompts, and the system will interpret the request, execute the appropriate tools against the file, and provide a summary of the results. As mentioned in the documentation:

The AI uses the REMnux MCP server to run the appropriate REMnux tools automatically. The MCP server offers guidance regarding the tools that the AI should consider, but it’s up to the AI agent to decide on the analysis workflow. And, of course, your interactions, requests, and observations can also direct the AI regarding the analysis steps.

Key capabilities available to AI assistants through the REMnux MCP server:

Analyze files based on detected type (PE, PDF, Office docs, scripts, ELF, etc.)

Get tool recommendations for a specific file without running them

Run specific REMnux tools directly, including piped commands

Extract indicators of compromise (IOCs) from text

Get usage help for any installed REMnux tool

I experimented with a few of the usual suspects in my corpus and provided pretty generic prompts like “analyze (file-xyz)” and “what are the IOCs?” The results were very positive – but I’ve only scratched the surface in testing.

Then I decided to see how adaptive this AI was and how easy it would be to make it aware of new tools and syntax. I provided the following:


MalChela tool suite is  installed in /home/remnux/Tools/MalChela
All are rust based tools so cd to the MalChela directory, and then ./target/release/fileanalyzer (path to executable) would be the syntax. 
The 4 tools below are the primary tools for static analysis.
  File Analyzer       |  Get the hash, entropy, packing, PE info, YARA and VT match status for a file  
  mStrings            |  Analyzes files with Sigma rules (YAML), extracts strings, matches ReGex. 
  NSRL Hash Lookup    |  Query an MD5 or SHA1 hash against NSRL
  Malware Hash Lookup |  Query a hash value against VirusTotal & Malware Bazaar

Immediately it began running the tools in MalChela against the malware file I was previously analyzing and provided a summary of the different tool results.

I plan to do a lot more testing but so far things are looking very promising.

So what do you think? Are you using AI in your malware analysis workflows? What capabilities of AI do you think are most useful when it comes to malware analysis? Let me know in the comments.

2025 Year in Review: Open Source DFIR Tools and Malware Analysis Projects

DFIR, Forensics, Mac, Malware, MITRE ATT&CK, PowerShell, Python, Raspberry Pi, Rust, SIgma, Triage, USB, yara

As 2025 draws to a close, I’m taking a moment to reflect on what turned out to be one of my most productive years in code. From major releases to entirely new projects, this year saw significant evolution across my DFIR toolkit—driven by real-world incident response needs, classroom teaching experiences, and late-night tinkering sessions fueled by good bourbon and better puzzles.

What started as continuing work on CyberPipe evolved into a year of substantial innovation: creating MalChela for YARA and malware analysis, building a portable Raspberry Pi forensics platform, developing automated timeline generation workflows, and crafting specialized utilities that solve specific problems I encountered in the field. Each tool represents not just lines of code, but practical solutions to challenges that digital forensics and incident response professionals face daily.

Whether you’re a seasoned forensic analyst, an incident responder building your toolkit, or a student just getting started in DFIR, my hope is that these open-source projects make your work a little easier and a lot more efficient. All tools remain freely available on GitHub, because I believe the best way to advance our field is to share knowledge and capabilities openly.

Here’s what kept me busy in 2025:

MalChela – YARA & Malware Analysis Toolkit (Rust)

My flagship project that evolved significantly throughout 2025:

March: Initial release – Combined 10 programs into one Rust workspace for YARA and malware analysis
May: v2.1 – Added smoother workflows, better third-party tool integration, and enhanced argument handling
May: v2.2 “REMnux Release” – Native support for REMnux, integrations with Volatility3, Tshark, YARA-X
June: v3.0 – Major update introducing Case Management system, FileMiner (replacing MismatchMiner), and tool suggestion capabilities based on file characteristics
July: v3.0.1 – Refinements to mStrings, improved MITRE mappings, “Select All” functionality, optimizations for running on Toby
August: v3.0.2 – Enhanced threat hunting with MITRE ATT&CK technique lookup

MalChela at a Glance

Rust-based malware analysis toolkit combining YARA scanning, file analysis, hash generation, string extraction with MITRE ATT&CK mapping, and automated malware sample extraction from password-protected archives
Multiple specialized utilities including mzhash/xmzhash for corpus generation, file type mismatch detection, entropy analysis, PE structure examination, and fuzzy hashing capabilities
Integrated threat intelligence with VirusTotal and Malware Bazaar API support, NSRL database queries for known-good file filtering, and Sigma rule application for IOC identification
Case management system (v3.0) featuring unified tracking of files, tools, and notes in case.yaml format with auto-saved outputs, tagging, search functionality, and VS Code integration
Extensible architecture supporting custom tool integration via tools.yamlconfiguration, enhanced support for Volatility 3, TShark, and YARA-X, with both GUI and CLI modes (WSL2-compatible on Windows)
Complete documentation embedded as PDF or online

MalChela v3.0: Case Management, FileMiner, and Smarter Triage

https://github.com/dwmetz/MalChela

CyberPipe – Incident Response Collection Tool (PowerShell)

Continued evolution of the enterprise digital evidence collection script:

May: v5.1 – Streamlined profiles with better flexibility, customizable collection profiles
October: v5.2 – Improved collection methods with dual disk space validation, SHA-256 hashing of artifacts, single-file reporting, network collection simplification
November: v5.3 – Critical PowerShell 5.1 compatibility fixes, dual validation logic, enhanced reliability across all PowerShell environments

CyberPipe v5.3: Enhanced PowerShell Compatibility and Reliability

https://github.com/dwmetz/CyberPipe

CyberPipe-Timeliner ✱New✱ (PowerShell)

November: CyberPipe-Timeliner – New companion project to CyberPipe that automates the workflow from Magnet Response collections to unified forensic timelines using Eric Zimmerman’s EZ Tools and ForensicTimeliner

CyberPipe-Timeliner: From Collection to Timeline in One Script

https://github.com/dwmetz/CyberPipe-Timeliner

Toby – Portable Raspberry Pi Forensics Toolkit

July: Released Toby – A compact forensics toolkit built on Raspberry Pi Zero 2 W running customized Kali Linux, designed for headless operation via SSH/VNC, perfect for field analysis and malware triage

Portable Forensics with Toby: A Raspberry Pi Toolkit

Toby-Find

July: Toby-Find – Terminal-based command-line helper tool for discovering CLI forensics tools in KALI and REMnux environments, created initially for university teaching

Toby-Find: Simplifying Command-Line Forensics Tools

https://github.com/dwmetz/Toby

Crabwise – USB Device Benchmark Utility (Rust)

August: Released Crabwise – A lightweight USB benchmarking tool that measures true read/write speeds of USB devices for forensic workflows. Tests write throughput with pseudo-random data and read performance under uncached conditions. Includes logging functionality to track performance across different cables, hubs, and connection paths, helping forensic investigators optimize their hardware setups.

Is your USB device slowing down your forensic investigation?

https://github.com/dwmetz/Crabwise

Toolbox Utilities – Specialized Python and Bash Scripts

Standalone tools maintained in the Toolbox repository:

October: CoreBreaker.py – Breaks large yara-rules-core files into smaller .yar files for tool ingestion
October: EtTu.py – Caesar cipher brute force decoder (created for Murdle puzzle solving); After all, All work and no play makes Jack a dull boy.
November: cloudtrail_timeline.py – Parses AWS CloudTrail JSON logs and outputs CSV format for Timeline Explorer
November: mac_triage_timeline.sh – Processes Mac-Triage ZIP files and generates timeline for Timeline Explorer
November: uac_timeline.sh – Processes UAC tar.gz files and generates timeline for Timeline Explorer (Linux/macOS)

https://github.com/dwmetz/Toolbox

All projects are available on my GitHub at github.com/dwmetz, with detailed documentation on bakerstreetforensics.com. My goal is making DFIR and malware analysis more accessible, automated, and efficient for incident responders and forensic analysts.

Enhance Threat Hunting with MITRE Lookup in MalChela 3.0.2

DFIR, Forensics, Malware, MITRE ATT&CK, Rust

Understanding adversary behavior is core to modern forensics and threat hunting. With the release of MalChela 3.0.2, I’ve added a new tool to your investigative belt: MITRE Lookup — a fast, offline way to search the MITRE ATT&CK framework directly from your MalChela workspace.

Whether you’re triaging suspicious strings, analyzing IOCs, or pivoting off YARA hits, MalChela can now help you decode tactics, techniques, and procedures without ever leaving your terminal or GUI. MITRE Lookup is powered by a local JSON snapshot of the ATT&CK framework (Enterprise Matrix), parsed at runtime with support for fuzzy searching and clean terminal formatting. No internet required.

What It Does

The MITRE_lookup tool lets you:

Search by Technique ID (e.g., T1027, T1566.001)
Search by topic or keyword (e.g., ‘RDP’, ‘Wizard Spider’)
Get tactic category, platforms, and detection guidance
Optionally include expanded content with the –full flag
Use from the CLI, MalChela launcher, or GUI modal

Example:

$ ./target/release/MITRE_lookup -- T1059.003

T1059.003 - Windows Command Shell

Tactic(s): execution

Platforms: Windows

Detection: Usage of the Windows command shell may be common on administrator, developer, or power user systems depending on job function. If scripting is restricted for normal users, then any attempt to enable scripts running on a system would be considered suspicious. If scripts are not commonly used on a system, but enabled, scripts running out of cycle from patching or other administrator functions are suspicious. Scripts should be captured from the file system when possible to determine their actions and intent...

GUI Integration

Select MITRE Lookup in the left-hand Toolbox menu
Use the input field at the top of the modal to enter a keyword or technique ID (e.g., `T1059` or `registry`)
Use the “Full” checkbox for un-truncated output
“Save to Case” option

Saving for Later

You can save MITRE Lookup results directly from the GUI, either as a standalone markdown file to a designated folder, or into the active Case Notes panel for later reference. This makes it easy to preserve investigative context, cite specific TTPs in reports, or build a threat narrative across multiple tools. The saved output uses clean Markdown formatting — readable in any editor or compatible with case management platforms. This feature is already live in v3.0.2 and will evolve further with upcoming case linkage support.

*Markdown view of a **MITRE_lookup** report*

Why MITRE ATT&CK in MalChela?

MalChela already focuses on contextual forensics — understanding not just what an artifact is, but why it matters. By embedding MITRE ATT&CK into your daily toolchain:

You reduce pivot fatigue from switching between tools/web tabs
You boost investigation speed during triage and reporting
You enable a more threat-informed analysis process

Whether you’re tagging findings, crafting YARA rules, or writing case notes, the MITRE integration helps turn technical output into meaningful insight — all from within the MalChela environment.