Is Wurst-Client-v7.54.1-MC26.2.jar Safe? JAR Virus and Malware Scan Report

[!WARNING] Final verdict available at the end of this report.

What This JAR Scanner Found

The static scan examined 801 classes (all of them were successfully de‑compiled) and identified 63 classes that triggered at least one “suspicious” indicator, giving a suspicious‑class ratio of about 8 %. Most of the alerts are related to normal file‑system use, network calls, or the use of encryption and reflection APIs that are common in feature‑rich Minecraft clients.

The scanner also noted 12 hard‑coded external URLs (the client’s own website, update servers, analytics, Microsoft/Xbox login endpoints, Mojang profile services, OpenAI, Google Translate, etc.) and a handful of process‑builder and crypto usages. No class was flagged for obvious credential‑stealing, hidden payload download, or destructive system commands.

Questions the Full Report Answers

• Does the JAR try to contact remote servers, and are those contacts expected for its functionality?
• Are the most suspicious indicators coming from the core cheat client or from bundled third‑party libraries?
• Is there any evidence of a remote‑access trojan, hidden downloader, or credential‑theft routine?
• How much of the code could be inspected by the decompiler, and were there any analysis gaps?

Malware and Virus Findings

The scan did not detect high‑signal malicious behavior such as:

• Direct credential theft (e.g., reading saved passwords and sending them out).
• Hidden download of additional executable code.
• System‑wide destructive commands or persistence mechanisms.

The only potentially concerning patterns are:

• Use of the MicrosoftLoginManager to obtain Xbox/Minecraft tokens (the user must supply their Microsoft credentials).
• A SkinStealer class that contacts Mojang’s session server to retrieve other players’ skin data.
• An Analytics component that sends usage events to plausible.wurstclient.net.

These are functional features of the cheat client rather than covert malware.

RAT Detection

No evidence was found that the JAR behaves like a Remote‑Access Trojan. It does not open a back‑door, listen for inbound commands, or execute arbitrary system commands beyond the limited ProcessBuilder helper used internally.

Suspicious Classes and Evidence

Core JAR or Mod Code

Class	Severity	Behavior	Evidence
MicrosoftLoginManager	Medium	Performs OAuth flow with Microsoft/Xbox endpoints to obtain Minecraft tokens.	Hard‑coded URLs to login.live.com, auth.xboxlive.com, api.minecraftservices.com; outbound HTTP calls.
SkinStealer	Low‑Medium	Queries Mojang’s session server for a player’s skin JSON.	Outbound URLs to sessionserver.mojang.com, api.mojang.com.
PlausibleAnalytics	Low	Sends usage events to the client’s analytics server.	URL https://plausible.wurstclient.net/api/event.
OpenAiMessageCompleter & ModelSettings	Low	Calls OpenAI’s completion API for chat‑based autocomplete.	URLs https://api.openai.com/....
GoogleTranslate	Low	Calls Google Translate to translate chat messages.	URLs https://translate.google.com/....
WurstUpdater & Version	Low	Checks GitHub releases and the client’s website for updates.	URLs to api.github.com and www.wurstclient.net.
MultiProcessingUtils	Low	Provides a helper to launch a new Java process.	process_builder_api indicator.
Encryption (alt manager)	Low‑Medium	Handles encrypted storage of alt‑account credentials.	Crypto API, Base64, file I/O.

Bundled Third‑Party Libraries

No separate third‑party libraries (e.g., Apache Commons, SLF4J) were flagged individually; the suspicious signals all originate from the client’s own code.

Network Activity

• Client website & update server: www.wurstclient.net (homepage, changelog, download, capes, tutorials).
• Analytics: plausible.wurstclient.net/api/event.
• Microsoft/Xbox login flow: login.live.com, user.auth.xboxlive.com, xsts.auth.xboxlive.com, api.minecraftservices.com, auth.xboxlive.com.
• Mojang profile services: sessionserver.mojang.com, api.mojang.com.
• OpenAI API: api.openai.com.
• Google Translate: translate.google.com.
• GitHub releases: api.github.com/repos/Wurst-Imperium/Wurst-MCX2/releases.

All outbound connections are hard‑coded URL literals used for legitimate features (authentication, updates, analytics, optional translation/completion services).

Deobfuscation and Analysis Coverage

• Decompilation success: 801/801 classes parsed, 0 failures.
• Anomalies: 2 classes required fallback decompilation due to timeouts or stack‑underflow; these are minor and do not hide large code blocks.
• Hard‑to‑review APIs: Base64, crypto, reflection, and class‑loader usage appear in the encryption and reflection helper classes, but the code was still visible to the scanner.

Is This Minecraft Mod Safe?

Yes, the file is a Minecraft cheat client (often called a “mod” for Fabric/Forge). Its purpose is to provide extra gameplay features, account management, and optional online services. The scan reflects the typical behavior of such a client.

What Looks Normal

• File‑system access for storing settings, profiles, keybinds, and encrypted alt accounts.
• Update checks against the client’s website and GitHub releases.
• Telemetry via Plausible analytics (common for open‑source projects).
• OAuth flow with Microsoft/Xbox to obtain a Minecraft access token (required for online authentication).
• Optional external services (Google Translate, OpenAI) that are only used when the user enables those features.
• Use of standard libraries (JSON handling, HTTP client, reflection) that trigger “hard‑to‑review” flags but are not malicious.

What Is Dangerous

• The SkinStealer class can download other players’ skin data; while not inherently harmful, it demonstrates the client’s ability to request data about arbitrary usernames.
• The MicrosoftLoginManager collects user‑provided Microsoft credentials; if a user were tricked into entering them, the client could forward the tokens to its own servers (the scan shows only the official Microsoft endpoints, not a third‑party exfiltration URL).
• ProcessBuilder usage could be leveraged to launch external Java processes, but the code only builds a process for internal purposes (e.g., launching a separate class).

No evidence of hidden payloads, ransomware, or remote command execution beyond the intended features.

What Should You Do?

1. If you trust the source (official Wurst‑Client releases) and need the cheat features, you may use the JAR, but be aware it will contact the listed external services.
2. Review the optional features (OpenAI, Google Translate, analytics) and disable them in the client’s settings if you prefer to limit network traffic.
3. Never enter your Microsoft credentials into a client you do not fully trust; the login flow is visible but still requires user interaction.
4. Keep the client updated; newer versions may address any privacy concerns.

Scan Limitations

Static analysis can flag suspicious patterns but cannot guarantee runtime safety. It cannot see what data the client actually sends after you interact with it, nor can it detect malicious behavior that only appears under specific game conditions. Always combine scanner results with reputable source verification and personal risk tolerance.

Frequently Asked Questions

Can a JAR file contain a virus?

Yes. A JAR is just a ZIP archive of Java bytecode, and it can contain malicious code that runs when the JAR is loaded.

How do I check whether a JAR file is safe?

Run a reputable static scanner (like the one used here), verify the publisher’s reputation, inspect the code if you can, and consider the network/permission behavior the JAR requests.

Can this scanner detect a Minecraft RAT?

It can highlight indicators typical of remote‑access trojans (process execution, hidden downloads, outbound connections to unknown servers). It will not guarantee detection, especially if the RAT is heavily obfuscated.

Does obfuscation mean a JAR is malicious?

Not necessarily. Many legitimate developers obfuscate code to protect intellectual property. However, heavy obfuscation combined with suspicious indicators can raise the risk level.

Final JAR Safety Verdict

Verdict: Use caution
Risk level: Medium
Confidence: High (based on full decompilation and clear mapping of network calls)

Should I trust this JAR, and why?
The Wurst‑Client JAR is a feature‑rich Minecraft cheat client that performs many legitimate actions: it reads and writes configuration files, checks for updates, authenticates with Microsoft/Xbox, and optionally contacts analytics, translation, and AI services. The scanner found no hidden downloaders, credential‑stealing routines, or remote‑control back‑doors. However, it does request user credentials for Microsoft login and can retrieve other players’ skin data, which may be privacy‑sensitive. Because the client reaches out to several external services and includes encryption/reflection code that is harder to audit, you should use it only if you are comfortable with those network interactions and have obtained the JAR from a trusted source. Disabling optional online features and keeping the client up‑to‑date will further reduce any remaining risk.