# vxunderground/MalwareSourceCode: a source-code archive for malware researchers

> A repository that collects malware source code across Windows, Linux, Android, macOS and scripting languages. It is a study archive, not a toolkit, and the README is explicit about the liability that comes with it.

**vxunderground/MalwareSourceCode** — Collection of malware source code for a variety of platforms in an array of different programming languages.

- Repository: https://github.com/vxunderground/MalwareSourceCode
- Website: https://vx-underground.org
- Stars: 18,758 · Forks: 2,101
- Language: Assembly
- License: not declared
- Published: 2026-09-21 · Updated: 2026-09-21 · Language: en
- Canonical page: https://hysenlabs.com/projects/vxunderground-malwaresourcecode

## What MalwareSourceCode is for

The repository describes itself as a "Collection of malware source code for a variety of platforms in an array of different programming languages." That single sentence sets the scope. This is not a detection tool, not a sandbox, and not a sample feed. It is a code archive: the source files behind Windows ransomware, Linux rootkits and botnets, PHP web shells, Android malware, macOS malware, and older targets such as MSDOS and Windows CE. The audience is narrow and specific. Reverse engineers who want to see how a family implements its persistence, students in a malware-analysis course who need readable code rather than a stripped binary, and detection engineers who want to write a rule against the way a loader actually builds its payload. If you are looking for something to install and run against a live endpoint, you are in the wrong repository.

## How the collection is organised on disk

The layout is by platform first and by category second. Top-level directories include Android, Engines, Java, Javascript, LegacyWindows, Libs, Linux, MSDOS, MacOS, Other, PHP, Panel, Perl, Phishing, PointOfSales, Python, Ruby and Win32. Under Linux the README lists subdirectories for Backdoors, Botnets, Infectors, Mirai-Family, Rootkits, Tools and Trojans. Under Win32 it lists Binders, Botnets, Crypters, Exploit kits, Infectors, Internet worms, Malware families, Ransomware, Rootkits and Stealers. PHP is split by family names such as C99, R57-shell, PhpSpy, Lanker and Macker. Engines is subdivided into BAT, Linux, VBS and Win32. One detail worth noticing: the README's file-structure list includes an MSIL entry that is struck through, and the actual top-level tree does not contain an MSIL directory. The README and the repository are not perfectly in sync, so browse the tree rather than trusting the list alone.

## Packaging, the 'infected' password, and what you actually download

The README's Notes section states that all source code which is packaged may or may not be set with the password 'infected', without the quote marks, and that individual files are likely not packaged. It also asks readers not to comment asking for the password, noting it was placed across vx-underground.org and the official vx-underground Twitter account. This matters for workflow. If you clone the repository and open an archive, some entries will prompt for a password and some will not. That inconsistency is acknowledged in the README rather than hidden, and it is a direct consequence of how the collection was assembled over time from different contributors. Plan for it: keep an extraction step in your lab procedure that tries the known password before assuming an archive is corrupt.

## Cloning the archive and browsing a first family

There are no build instructions in the README, because this is an archive rather than a project you compile. The README points readers to the vx-underground site and its samples page for downloads, and the repository itself is the source collection. The README gives no clone command, so the only concrete navigation aid it provides is the file-structure list, which names the top-level directories: Android, Engines, Java, Javascript, LegacyWindows, Libs, Linux, MSDOS, MacOS, Other, PHP, Panel, Perl, Phishing, PointOfSales, Python, Ruby and Win32. From there you pick a platform and a category rather than a single entry point. Under Linux the README lists Backdoors, Botnets, Infectors, Mirai-Family, Rootkits, Tools and Trojans; under Win32 it lists Binders, Botnets, Crypters, Exploit kits, Infectors, Internet worms, Malware families, Ransomware, Rootkits and Stealers. Work inside a virtual machine or a container with no network access and no shared folders. The repository is source code, but some entries include build scripts, and the README's liability disclaimer makes clear that vx-underground accepts no responsibility for what results from your access to the resource.

## What the archive does not give you

There is no licence file in the repository, and the README does not state terms for reuse. That is the single biggest practical limitation. Code contributed from leaked or captured sources does not arrive with a clean rights chain, and the repository does not attempt to supply one. If your organisation has a legal review step for third-party code, this collection will not pass it in its current form, and you should treat every file as read-only research material rather than something to incorporate. The second limitation is coverage bias. The collection is heavy on Windows and PHP families and on publicly known or leaked code. It says nothing about how representative it is of what is currently in circulation. A detection rule written only from these sources will match the families that happen to be archived here and miss everything else. The third is that source is not behaviour: a family whose source is present may have been compiled with different flags, packed, or updated since, so the archived code is a reference point, not a ground truth for what a sample does at runtime.

## How it differs from VirusShare and sample repositories

VirusShare distributes malware samples: binaries, hashes and metadata, which you analyse with a disassembler or a sandbox. This repository distributes source. The difference changes what you can do with it. With a binary you reconstruct intent from machine code and often lose names, comments and structure. With source you read the original variable names and control flow, which is why the archive is useful for teaching and for writing detection logic against a specific implementation. The trade-off runs the other way too. A sample repository gives you the artefact that actually ran in the wild, with its packing and obfuscation intact. A source archive gives you code that may never have been compiled in that form. Researchers who need runtime behaviour still need a sample source; researchers who need to understand a technique are better served here.

## Maintenance, upgrade cost and licence implications

The repository is not archived, and the last push was on 2026-05-30. That is roughly four months before the current date, so the collection is still receiving changes, but the README does not describe a release process, versioning scheme or changelog. There are no releases listed. Upgrading therefore means pulling the branch again, and because entries are added and reorganised rather than versioned, a pull can move files you were citing. If you reference a path in your own notes or tooling, pin the commit hash you cloned rather than tracking main. On licensing, the repository declares no licence. The README's liability disclaimer limits vx-underground's responsibility for damages arising from access to the resource, but it says nothing about what you may do with the code inside. That is a question for your own legal review, not something the repository answers, and it is the first thing to resolve before any of this material enters a product or a shared internal corpus.

## Conclusion

Adopt it if you are a malware analyst, reverse engineer, detection engineer or academic studying how real families are written, and you can keep the material inside an isolated lab. Do not adopt it if you want a scanner, a signature feed or anything you can run on a production host; the repository is raw source, and the README carries an explicit liability disclaimer for anyone who accesses it. Before you rely on it, check the licence situation, because the repository does not declare one, and confirm the current top-level directories, since the README's file-structure list and the actual tree already differ.

## FAQ

### Can you give me an example of malware code from MalwareSourceCode?

Yes. The repository is organised so you can open a platform directory and read the source directly, for example under Linux/Botnets, Linux/Rootkits or Win32/Ransomware. The README does not describe individual families, so browse the tree to find a specific one.

### What code is malware written in in the MalwareSourceCode collection?

The repository covers a range of languages and platforms, including Assembly as the primary language, plus Java, Javascript, PHP, Perl, Python and Ruby directories, alongside C-style Windows and Linux code. The README's file structure lists the categories under each platform.

### What are the common sources of malware in a collection like MalwareSourceCode?

The repository does not document provenance for individual entries. What the README does say is that packaged source may be protected with the password 'infected', and it credits a list of contributors who submitted content.

### Does MalwareSourceCode include a tool to check code for viruses?

No. The repository is a source-code archive, not a scanner or detection engine. The README describes it as a collection of malware source code and provides no scanning functionality.

## Sources

- [Issues](https://github.com/vxunderground/MalwareSourceCode/issues)
- [Project website](https://vx-underground.org)
- [README](https://github.com/vxunderground/MalwareSourceCode/blob/main/README.md)
- [vxunderground/MalwareSourceCode on GitHub](https://github.com/vxunderground/MalwareSourceCode)

---

Hysen Labs editorial analysis, written from the project's own repository and release notes. Cite the canonical page: https://hysenlabs.com/projects/vxunderground-malwaresourcecode