Improper Output Neutralization for Logs
The product does not neutralize or incorrectly neutralizes output that is written to logs.
Log injection attacks occur when user input is written to log files without proper sanitization. This can allow attackers to forge log entries, inject malicious content, or exploit log analysis tools.
이 취약점을 수정하는 방법
4개의 Shoulder 탐지 규칙을 기반으로 한 Log Injection 예방 전략.
Strip newlines and control characters from user input before logging
package main import ( "log" "net/http" - ) - - func handler(w http.ResponseWriter, r *http.Request) { - username := r.URL.Query().Get("user") - // Vulnerable: user input logged directly - log.Printf("Login attempt for user: %s", username) + "strings" + ) + + func sanitizeLogInput(s string) string { + s = strings.ReplaceAll(s, "\n", "") + s = strings.ReplaceAll(s, "\r", "") + return s + } + + func handler(w http.ResponseWriter, r *http.Request) { + username := r.URL.Query().Get("user") + // Safe: newlines stripped before logging + log.Printf("Login attempt for user: %s", sanitizeLogInput(username)) }
Strip newline characters from user input before writing to log files
const express = require('express'); const winston = require('winston'); const app = express(); app.post('/login', (req, res) => { - const username = req.body.username; + const username = req.body.username.replace(/[\r\n]/g, ''); winston.info(`Login attempt: ${username}`); res.json({ status: 'ok' }); });
Sanitize user input by stripping CRLF characters before writing to logs
- app.post('/login', (req, res) => { - logger.info(`Login attempt from: ${req.body.username}`); + const sanitize = (str) => str.replace(/[\r\n]/g, '').substring(0, 200); + + app.post('/login', (req, res) => { + logger.info('Login attempt', { username: sanitize(req.body.username) }); });
Use structured logging with separate fields for user data instead of string interpolation
import logging from flask import request - @app.route('/login', methods=['POST']) - def login(): - username = request.form.get('username') - logging.info(f"Login attempt for user: {username}") + logger = logging.getLogger(__name__) + + @app.route('/login', methods=['POST']) + def login(): + username = request.form.get('username', '') + logger.info("Login attempt", extra={'username': username}) return "OK"
코드에서 취약점 찾기
Shoulder를 사용하여 코드에서 Improper Output Neutralization for Logs 패턴을 스캔하세요. 4 규칙.
# Scan with Shoulder CLI npx @shoulderdev/cli trust --cwe=117 # Or scan entire project npx @shoulderdev/cli trust .
탐지 규칙 (4)
코드 리뷰에서 주의할 점
이 패턴은 잠재적인 Improper Output Neutralization for Logs 취약점을 나타냅니다. 코드 리뷰와 보안 감사 중에 찾아보세요.
코드베이스를 스캔하세요: Improper Output Neutralization for Logs
Shoulder CLI는 전체 코드베이스에서 취약한 패턴을 찾아냅니다.