Analyzing Java Jar Malware
Analyzes Java/JAR malware (such as Adwind/jRAT-class cross-platform RATs) by
Install
$ agentstack add skill-meltedinhex-analyst-ai-pack-analyzing-java-jar-malware ✓ scanned · ✓ verified, works with Claude Code, Cursor, and more.
Security review
✓ PassedNo issues found. Passed automated security review. · v0.1.0 How review works →
- ✓ Prompt-injection patterns
- ✓ Secret / credential exfiltration
- ✓ Dangerous shell & filesystem operations
- ✓ Untrusted network calls
- ✓ Known-malicious package signatures
What it can access
- ● Network access Used
- ✓ Filesystem access No
- ● Shell / process execution Used
- ✓ Environment & secrets No
- ✓ Dynamic code execution No
From automated source analysis of v0.1.0. “Used” means the capability is present in the source — more access means more to trust, not that it’s unsafe.
Verified badge
Passed review? Show it. Paste this badge into your README, it links to the public security report.
Links to your public security report.[](https://agentstack.voostack.com/security/report/skill-meltedinhex-analyst-ai-pack-analyzing-java-jar-malware) Reliability & compatibility
Declared compatibility
Compatibility is declared by the source manifest. End-to-end runtime verification is coming, see below.
We're building live execution health for every listing: tool-call success rate, median latency, uptime, and last-checked timestamps, measured, not self-reported. It isn't live yet, so we don't show numbers we can't stand behind.
How agent discovery & health will work →About
Analyzing Java/JAR Malware
When to Use
- You have a malicious or suspicious
.jar(often a cross-platform RAT) and need to map its
structure, entry point, obfuscation, and capability surface before decompiling.
- You want to triage a Java payload without running the JVM.
Do not use java -jar to run it — that executes the malware. Treat the JAR as a ZIP and read its contents statically.
Prerequisites
- The JAR file, read inertly. Optional: a Java decompiler (CFR, Procyon) for the next stage.
Safety & Handling
- Read the archive statically; never launch the JVM on the sample. Defang any URLs found.
Workflow
Step 1: Inventory the archive and entry point
python scripts/analyst.py inspect sample.jarLists .class files, embedded resources/payloads (nested JARs, scripts, encrypted blobs), and reads META-INF/MANIFEST.MF for Main-Class/Premain-Class.
Step 2: Detect obfuscation and packers
Flags obfuscator fingerprints (Allatori, ProGuard, Zelix), single-character class/package names, and string-decryption indicators.
Step 3: Flag capability classes
Surface dangerous API usage in strings/constant pools: Runtime.exec/ProcessBuilder, java.lang.reflect, URLClassLoader, javax.crypto, java.net.Socket, registry/persistence helpers.
Step 4: Route to decompilation
Hand the key classes to a decompiler (CFR/Procyon) for source recovery; record IOCs.
Validation
- The manifest entry point is read and reported.
- Embedded payloads/nested archives are enumerated.
- Capability flags are backed by concrete class/string evidence.
Pitfalls
- String-encrypted samples where capability strings appear only after decryption.
- Multi-stage droppers that unpack a second JAR at runtime.
- Benign obfuscated commercial JARs — corroborate with capability and delivery context.
References
- See [
references/api-reference.md](references/api-reference.md) for the inspector. - JVM/JAR format and ATT&CK T1027 references (linked in frontmatter).
Source & license
This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.
- Author: meltedinhex
- Source: meltedinhex/analyst-ai-pack
- License: Apache-2.0
- Homepage: https://meltedinhex.com/
Install and usage instructions live in the source repository linked above.
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Versions
- v0.1.0 Imported from the upstream source.