修复多项安全漏洞和Bug

1. 安全修复：
   - 修复密码重置接口用户枚举漏洞，统一返回消息防止信息泄露
   - 统一密码强度验证为8位以上且包含字母和数字
   - 添加第三方账号密码加密存储(Fernet对称加密)
   - 修复默认管理员弱密码问题，改用随机生成强密码
   - 修复管理员回复XSS漏洞，添加HTML转义
   - 将MD5哈希替换为SHA256

2. 并发Bug修复：
   - 修复日志缓存竞态条件，添加锁保护
   - 修复截图信号量配置变更后不生效问题

3. 其他改进：
   - 添加API参数类型验证和边界检查
   - 新增crypto_utils.py加密工具模块

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

database.py

@@ -26,6 +26,7 @@ from password_utils import (
     verify_password_sha256
 )
 from app_config import get_config
+from crypto_utils import encrypt_password, decrypt_password, migrate_password
 
 # 获取配置
 config = get_config()
@@ -473,7 +474,14 @@ def _migrate_to_v5(conn):
 # ==================== 管理员相关 ====================
 
 def ensure_default_admin():
-    """确保存在默认管理员账号 admin/admin"""
+    """确保存在默认管理员账号
+
+    安全修复：使用随机生成的强密码代替弱密码'admin'
+    首次运行时会将密码打印到控制台，请及时修改
+    """
+    import secrets
+    import string
+
     with db_pool.get_db() as conn:
         cursor = conn.cursor()
 
@@ -482,14 +490,22 @@ def ensure_default_admin():
         result = cursor.fetchone()
 
         if result['count'] == 0:
-            # 创建默认管理员 admin/admin
-            default_password_hash = hash_password_bcrypt('admin')
+            # 安全修复：生成随机强密码（12位，包含大小写字母和数字）
+            alphabet = string.ascii_letters + string.digits
+            random_password = ''.join(secrets.choice(alphabet) for _ in range(12))
+
+            default_password_hash = hash_password_bcrypt(random_password)
             cursor.execute(
                 'INSERT INTO admins (username, password_hash) VALUES (?, ?)',
                 ('admin', default_password_hash)
             )
             conn.commit()
-            print("✓ 已创建默认管理员账号 (admin/admin)")
+            print("=" * 60)
+            print("安全提醒：已创建默认管理员账号")
+            print(f"用户名: admin")
+            print(f"密码: {random_password}")
+            print("请立即登录后修改密码！")
+            print("=" * 60)
             return True
         return False
 
@@ -812,32 +828,45 @@ def delete_user(user_id):
 # ==================== 账号相关 ====================
 
 def create_account(user_id, account_id, username, password, remember=True, remark=''):
-    """创建账号"""
+    """创建账号（密码加密存储）"""
     with db_pool.get_db() as conn:
         cursor = conn.cursor()
+        # 安全修复：加密存储第三方账号密码
+        encrypted_password = encrypt_password(password)
         cursor.execute('''
             INSERT INTO accounts (id, user_id, username, password, remember, remark)
             VALUES (?, ?, ?, ?, ?, ?)
-        ''', (account_id, user_id, username, password, 1 if remember else 0, remark))
+        ''', (account_id, user_id, username, encrypted_password, 1 if remember else 0, remark))
         conn.commit()
         return cursor.lastrowid
 
 
 def get_user_accounts(user_id):
-    """获取用户的所有账号"""
+    """获取用户的所有账号（自动解密密码）"""
     with db_pool.get_db() as conn:
         cursor = conn.cursor()
         cursor.execute('SELECT * FROM accounts WHERE user_id = ? ORDER BY created_at DESC', (user_id,))
-        return [dict(row) for row in cursor.fetchall()]
+        accounts = []
+        for row in cursor.fetchall():
+            account = dict(row)
+            # 安全修复：解密第三方账号密码（兼容旧数据）
+            account['password'] = decrypt_password(account.get('password', ''))
+            accounts.append(account)
+        return accounts
 
 
 def get_account(account_id):
-    """获取单个账号"""
+    """获取单个账号（自动解密密码）"""
     with db_pool.get_db() as conn:
         cursor = conn.cursor()
         cursor.execute('SELECT * FROM accounts WHERE id = ?', (account_id,))
         row = cursor.fetchone()
-        return dict(row) if row else None
+        if row:
+            account = dict(row)
+            # 安全修复：解密第三方账号密码（兼容旧数据）
+            account['password'] = decrypt_password(account.get('password', ''))
+            return account
+        return None
 
 
 def update_account_remark(account_id, remark):
@@ -1483,17 +1512,22 @@ def get_feedback_by_id(feedback_id):
 
 
 def reply_feedback(feedback_id, admin_reply):
-    """管理员回复反馈"""
+    """管理员回复反馈（带XSS防护）"""
+    from app_security import escape_html
+
     with db_pool.get_db() as conn:
         cursor = conn.cursor()
         cst_tz = pytz.timezone("Asia/Shanghai")
         cst_time = datetime.now(cst_tz).strftime("%Y-%m-%d %H:%M:%S")
 
+        # 安全修复：转义管理员回复，防止存储型XSS攻击
+        safe_reply = escape_html(admin_reply) if admin_reply else ''
+
         cursor.execute('''
             UPDATE bug_feedbacks
             SET admin_reply = ?, status = 'replied', replied_at = ?
             WHERE id = ?
-        ''', (admin_reply, cst_time, feedback_id))
+        ''', (safe_reply, cst_time, feedback_id))
 
         conn.commit()
         return cursor.rowcount > 0