2nd/10_Wiki/Topics/DevOps_and_Security/SAST.md

---
id: wiki-2026-0508-sast
title: SAST
category: 10_Wiki/Topics
status: verified
canonical_id: self
aliases: [Static Application Security Testing, static analysis, source code analysis]
duplicate_of: none
source_trust_level: A
confidence_score: 0.95
verification_status: applied
tags: [security, sast, devsecops, static-analysis, ci-cd]
raw_sources: []
last_reinforced: 2026-05-10
github_commit: pending
tech_stack:
  language: multi
  framework: semgrep-codeql-snyk
---

# SAST

## 매 한 줄
> **"매 source 의 reading 없이 의 running"**. SAST (Static Application Security Testing) 의 source code, bytecode, binary 의 의 inspecting 의 vulnerabilities 의 detecting 의 — 매 runtime 의 없이. 2026 의 dominant tools: Semgrep (rule-based, fast), CodeQL (semantic, deep), Snyk Code (DeepCode AI).

## 매 핵심

### 매 SAST 의 기본 mechanics
- **AST/CFG/DFG**: source 의 parse → AST → control-flow graph → data-flow graph.
- **Taint analysis**: 매 source (user input) → sink (sql query) 의 path 의 trace.
- **Pattern matching**: 매 known anti-pattern (e.g., `eval(req.body)`) 의 detect.
- **Symbolic execution** (heavy): 매 path constraints 의 SMT solver 의 — 매 CodeQL.

### 매 modern tools 의 비교
- **Semgrep** (2026): YAML rules, 매 fast (CI-friendly), 매 OSS + Pro (Semgrep Code).
- **CodeQL** (GitHub): semantic queries, 매 deep — 매 GitHub Advanced Security 에 free for OSS.
- **Snyk Code**: AI-augmented (DeepCode), 매 fast, 매 commercial.
- **SonarQube**: code quality + security 의 hybrid.

### 매 응용
1. PR-blocking gate (block-on-high).
2. Pre-commit (fast subset).
3. Nightly full scan + Jira issue 의 auto-create.

## 💻 패턴

### Semgrep custom rule (taint TS)
```yaml
rules:
  - id: dangerous-eval-from-request
    languages: [typescript, javascript]
    severity: ERROR
    message: 매 user input 의 eval 의 — RCE 위험
    mode: taint
    pattern-sources:
      - pattern-either:
          - pattern: req.body
          - pattern: req.query
          - pattern: req.params
    pattern-sinks:
      - pattern-either:
          - pattern: eval(...)
          - pattern: new Function(...)
```

### GitHub Actions — Semgrep CI
```yaml
name: SAST
on: [pull_request]
jobs:
  semgrep:
    runs-on: ubuntu-latest
    container: returntocorp/semgrep
    steps:
      - uses: actions/checkout@v4
      - run: semgrep ci --config=p/owasp-top-ten --config=.semgrep/
        env:
          SEMGREP_APP_TOKEN: ${{ secrets.SEMGREP_APP_TOKEN }}
```

### CodeQL query 의 hardcoded secret
```ql
import javascript

from StringLiteral s
where s.getValue().regexpMatch("AKIA[0-9A-Z]{16}")
select s, "매 hardcoded AWS key 의 detected"
```

### Pre-commit hook — fast subset
```bash
#!/usr/bin/env bash
changed=$(git diff --cached --name-only --diff-filter=ACMR | grep -E '\.(ts|tsx|js|py)$')
[ -z "$changed" ] && exit 0
echo "$changed" | xargs semgrep --config=p/security-audit --error
```

### SARIF upload 의 GitHub code scanning 의
```yaml
- run: semgrep ci --sarif --output=semgrep.sarif || true
- uses: github/codeql-action/upload-sarif@v3
  with: { sarif_file: semgrep.sarif }
```

### Triage — false positive 의 suppress 의
```typescript
// nosemgrep: dangerous-eval-from-request
// 매 reason: input 의 zod-validated 의 already
const result = eval(safeMath); // ok
```

## 매 결정 기준
| 상황 | Tool |
|---|---|
| OSS project, 매 fast feedback | Semgrep (free OSS rules) |
| GitHub repo, 매 deep semantic | CodeQL (GHAS) |
| polyglot enterprise | Snyk Code or SonarQube |
| custom org rules 의 heavy | Semgrep Pro |

**기본값**: Semgrep (PR gate, p/owasp-top-ten) + CodeQL (nightly, scheduled).

## 🔗 Graph
- 부모: [[CI_CD 파이프라인 및 IDE 통합 보안|DevSecOps]] · [[Application Security]]
- 변형: [[보안_및_시스템_신뢰성_표준|DAST]] · [[IAST]] · [[SCA_Fundamentals|SCA]]
- 응용: [[보안_및_시스템_신뢰성_표준|OWASP Top 10]] · [[Secure SDLC]]
- Adjacent: [[CodeQL]] · [[Semgrep]]

## 🤖 LLM 활용
**언제**: triaging findings, generating fix PRs (Copilot Autofix style), writing custom rules from natural language.
**언제 X**: trusting AI-only triage 없이 의 human review — 매 false positives 여전히 30-50%.

## ❌ 안티패턴
- **Block-on-everything**: medium severity 의 PR block — devs 의 SAST 의 disable 의.
- **No suppression hygiene**: `nosemgrep` 의 reason 없이 spammed.
- **Tool-only**: SAST 만 — DAST/SCA 없으면 runtime + dependency 의 blind.
- **Scan once a quarter**: 매 finding backlog 의 explode.

## 🧪 검증 / 중복
- Verified (Semgrep Registry 2026, GitHub CodeQL docs, OWASP SAST guide).
- 신뢰도 A.

## 🕓 Changelog
| 날짜 | 변경 |
|---|---|
| 2026-05-08 | Phase 1 |
| 2026-05-10 | Manual cleanup — Semgrep/CodeQL 의 modern SAST patterns |