AI Code Review & Fuzzing

# AI-assisted code review framework
# Works with: GPT-4o, Claude 3.5 Sonnet, DeepSeek-Coder, local models via Ollama

import openai
from pathlib import Path

SECURITY_AUDIT_PROMPT = """You are an expert security code reviewer. Analyse the following code for:

1. **Injection vulnerabilities**: SQL injection, command injection, LDAP injection, XSS
2. **Authentication/Authorisation flaws**: Broken auth, IDOR, privilege escalation
3. **Cryptographic issues**: Weak algorithms, hardcoded keys, improper random
4. **Memory safety**: Buffer overflows, use-after-free (for C/C++/Rust unsafe)
5. **Deserialization**: Unsafe deserialization of user input
6. **SSRF / Path traversal**: Server-side request forgery, directory traversal
7. **Race conditions**: TOCTOU, missing locks on shared state
8. **Secrets exposure**: API keys, tokens, passwords in source
9. **Dependency risks**: Known-vulnerable library patterns

For each finding:
- Severity: CRITICAL / HIGH / MEDIUM / LOW / INFO
- Vulnerable code: Quote the exact line(s)
- Impact: What an attacker can achieve
- CWE: Map to CWE ID
- Remediation: Specific fix with code example

If no vulnerabilities are found, state that explicitly. Do not invent findings."""

def audit_file(filepath: str, model: str = "gpt-4o") -> str:
    """Audit a single source file for security vulnerabilities."""
    code = Path(filepath).read_text()
    
    response = openai.chat.completions.create(
        model=model,
        messages=[
            {"role": "system", "content": SECURITY_AUDIT_PROMPT},
            {"role": "user", "content": f"File: {filepath}\n\n```\n{code}\n```"}
        ],
        temperature=0.1  # Low temp → more precise, fewer hallucinations
    )
    return response.choices[0].message.content

def audit_directory(directory: str, extensions: list = None):
    """Audit all matching files in a directory tree."""
    if extensions is None:
        extensions = ['.py', '.js', '.ts', '.go', '.c', '.cpp', '.java', '.rs', '.php', '.rb']
    
    findings = []
    for path in Path(directory).rglob('*'):
        if path.suffix in extensions and path.is_file():
            print(f"Auditing: {path}")
            result = audit_file(str(path))
            if "no vulnerabilities" not in result.lower():
                findings.append({"file": str(path), "findings": result})
    
    return findings

# Example: audit a Python web app
results = audit_directory("./target-app/src/", ['.py'])
for r in results:
    print(f"\n{'='*60}")
    print(f"FILE: {r['file']}")
    print(r['findings'])

# For sensitive client code, use local models — zero data leaves your machine

# Install Ollama
curl -fsSL https://ollama.com/install.sh | sh

# Pull a coding-focused model
ollama pull deepseek-coder-v2:16b     # Strong at code analysis
ollama pull codellama:34b             # Meta's code LLM
ollama pull qwen2.5-coder:32b        # Alibaba's code model

# Run audit against local model (OpenAI-compatible API)
export OPENAI_API_BASE=http://localhost:11434/v1
export OPENAI_API_KEY=ollama  # Ollama doesn't need a real key

# Or use Ollama's native API:
curl http://localhost:11434/api/generate -d '{
  "model": "deepseek-coder-v2:16b",
  "prompt": "Review this code for security vulnerabilities:\n\n<paste code>",
  "stream": false
}'

# Step 1: Run Semgrep to get candidate findings
pip install semgrep

# Scan with security-focused rules
semgrep scan --config=p/security-audit \
             --config=p/owasp-top-ten \
             --config=p/cwe-top-25 \
             --json --output findings.json \
             ./target-app/

# Step 2: Feed findings to LLM for triage
import json
import openai

with open("findings.json") as f:
    semgrep_results = json.load(f)

TRIAGE_PROMPT = """You are a security expert triaging Semgrep findings.
For each finding, determine:
1. Is this a TRUE positive or FALSE positive? Explain why.
2. If true positive: severity, exploitability, and recommended fix.
3. If false positive: why the code is actually safe.

Be conservative — when in doubt, flag it for manual review."""

for finding in semgrep_results.get("results", []):
    context = f"""
Rule: {finding['check_id']}
Severity: {finding['extra']['severity']}
Message: {finding['extra']['message']}
File: {finding['path']}:{finding['start']['line']}
Code: {finding['extra']['lines']}
"""
    response = openai.chat.completions.create(
        model="gpt-4o",
        messages=[
            {"role": "system", "content": TRIAGE_PROMPT},
            {"role": "user", "content": context}
        ],
        temperature=0.1
    )
    print(f"\n--- {finding['path']}:{finding['start']['line']} ---")
    print(response.choices[0].message.content)

# Using Google's OSS-Fuzz-Gen approach: LLM generates fuzz harnesses
# from source code, then runs them with coverage-guided fuzzing

# Step 1: Clone target and OSS-Fuzz-Gen
git clone https://github.com/google/oss-fuzz-gen.git
cd oss-fuzz-gen

# Step 2: Generate a fuzz harness for a target function
# The LLM reads the function signature, documentation, and usage examples
# then writes a harness that exercises the function with fuzz-generated inputs

python generate_harness.py \
  --target-repo /path/to/target \
  --function "parse_input" \
  --model gpt-4o \
  --output harness.c

# Step 3: Compile and run with AFL++ or libFuzzer
clang -fsanitize=fuzzer,address -o fuzz_target harness.c target.c
./fuzz_target -max_len=4096 -timeout=10 corpus/

# Step 4: Let the LLM analyse crashes
python analyse_crash.py \
  --crash crash-*.txt \
  --source /path/to/target \
  --model gpt-4o

# Complete AI code review pipeline
# Combines: Semgrep → LLM triage → Deep analysis → Report generation

#!/bin/bash
set -e

TARGET_DIR="$1"
OUTPUT_DIR="./audit-results"
mkdir -p "$OUTPUT_DIR"

echo "[1/4] Running Semgrep SAST scan..."
semgrep scan --config=auto --json --output "$OUTPUT_DIR/semgrep.json" "$TARGET_DIR"

echo "[2/4] LLM triage of Semgrep findings..."
python ai_triage.py \
  --findings "$OUTPUT_DIR/semgrep.json" \
  --model deepseek-coder-v2 \
  --output "$OUTPUT_DIR/triaged.json"

echo "[3/4] Deep AI analysis of critical files..."
python ai_deep_review.py \
  --directory "$TARGET_DIR" \
  --focus "auth,payment,upload,api" \
  --model gpt-4o \
  --output "$OUTPUT_DIR/deep-review.md"

echo "[4/4] Generating report..."
python ai_report.py \
  --triaged "$OUTPUT_DIR/triaged.json" \
  --deep "$OUTPUT_DIR/deep-review.md" \
  --output "$OUTPUT_DIR/security-audit-report.md"

echo "Done! Report: $OUTPUT_DIR/security-audit-report.md"