diff --git a/SECURITY_ENHANCEMENTS.md b/SECURITY_ENHANCEMENTS.md
new file mode 100644
index 00000000..15f69473
--- /dev/null
+++ b/SECURITY_ENHANCEMENTS.md
@@ -0,0 +1,183 @@
+# Security Enhancements
+
+## Overview
+
+This document describes the security enhancements implemented to prevent malicious code injection attacks in Qinglong.
+
+## Issue Background
+
+A security vulnerability was discovered where malicious code could be injected into the system through:
+1. Cron task fields (`task_before`, `task_after`, `command`)
+2. Configuration file writes (`config.sh`, `extra.sh`, etc.)
+
+The reported incident involved a malicious script that:
+- Downloaded an external binary (`.fullgc`) from a suspicious domain
+- Executed the binary in the background
+- Persisted by continuously re-injecting itself
+
+## Security Fixes Implemented
+
+### 1. Input Validation for Cron Tasks
+
+**File:** `/back/validation/schedule.ts`
+
+Added comprehensive validation to detect and block dangerous shell patterns:
+
+- **Command Substitution**: Blocks `$(...)` and backtick patterns that could execute hidden commands
+- **File Downloads**: Blocks `curl`, `wget`, `fetch` commands
+- **External URLs**: Blocks HTTP/HTTPS URLs to prevent external resource downloads
+- **Hidden Files**: Blocks references to files starting with `.` (common in malware)
+- **Background Execution**: Blocks suspicious `nohup` patterns
+- **Output Hiding**: Blocks redirects to `/dev/null` combined with background execution
+- **Obfuscation**: Blocks `base64`, `decode`, `eval` patterns
+- **Temp Directory Execution**: Blocks execution from `/tmp` or hidden directories
+
+### 2. Config File Content Security
+
+**File:** `/back/api/config.ts`
+
+Enhanced validation for configuration file content to prevent:
+
+- Downloads followed by execution (`curl | bash`, `wget | bash`)
+- Download and permission changes (`curl && chmod +x`)
+- Suspicious executable downloads (files like `.fullgc`)
+- Background execution of hidden files
+
+### 3. Improved Shell Escaping
+
+**File:** `/back/services/cron.ts`
+
+Replaced weak shell escaping with a robust `escapeShellArg()` function that:
+
+- Properly escapes single quotes using `'\\''` pattern
+- Normalizes whitespace and newlines
+- Prevents command injection through various shell metacharacters
+
+## Security Best Practices
+
+### For Administrators
+
+1. **Review Existing Tasks**: Audit all existing cron tasks for suspicious patterns
+2. **Monitor Logs**: Check logs for security validation warnings
+3. **Update Dependencies**: Keep all npm/pip dependencies up to date
+4. **Limit Access**: Restrict who can create/modify cron tasks and config files
+5. **Regular Backups**: Maintain backups of configuration files
+
+### For Users
+
+1. **Trusted Sources Only**: Only add scripts from trusted repositories
+2. **Code Review**: Review any script before adding it to your cron tasks
+3. **Avoid External URLs**: Don't include download commands in task hooks
+4. **Report Suspicious Activity**: Report any unusual system behavior immediately
+
+## Validation Error Messages
+
+When the security system blocks a pattern, you'll see error messages like:
+
+- `命令包含潜在危险的模式，已被安全系统拦截` - Command contains dangerous pattern
+- `前置命令包含潜在危险的模式，已被安全系统拦截` - task_before contains dangerous pattern
+- `后置命令包含潜在危险的模式，已被安全系统拦截` - task_after contains dangerous pattern
+- `配置文件内容包含潜在危险的模式，已被安全系统拦截` - Config file contains dangerous pattern
+
+## What to Do If You're Affected
+
+If you've been affected by the malicious code injection:
+
+### 1. Immediate Actions
+
+```bash
+# Stop and remove the malicious process
+pkill -f ".fullgc"
+rm -f /ql/data/db/.fullgc
+
+# Check for the malicious code in configuration files
+grep -r "fullgc" /ql/data/config/
+grep -r "551911.xyz" /ql/data/config/
+```
+
+### 2. Clean Configuration Files
+
+```bash
+# Backup current configs
+cp -r /ql/data/config /ql/data/config.backup
+
+# Review and clean these files:
+# - /ql/data/config/config.sh
+# - /ql/data/config/extra.sh
+# - /ql/data/config/task_before.sh
+# - /ql/data/config/task_after.sh
+
+# Remove any lines containing:
+# - Downloads (curl, wget)
+# - External URLs
+# - .fullgc references
+```
+
+### 3. Review Cron Tasks
+
+1. Log into Qinglong admin panel
+2. Check all cron tasks for suspicious content in:
+   - Command field
+   - task_before field
+   - task_after field
+3. Delete or clean any suspicious tasks
+
+### 4. Update to Patched Version
+
+Ensure you're running a version of Qinglong with these security fixes.
+
+### 5. Change Credentials
+
+If you suspect compromise:
+- Change your Qinglong admin password
+- Review and rotate any API tokens
+- Check for unauthorized access in logs
+
+## Detection
+
+### Log Analysis
+
+Security events are logged to help detect attempted attacks:
+
+```bash
+# Check for security validation failures in logs
+grep "安全系统拦截" /ql/data/log/*.log
+
+# Check for suspicious file modifications
+grep "配置文件写入" /ql/data/log/*.log
+```
+
+### File Integrity
+
+Regularly check for unexpected files:
+
+```bash
+# Find hidden executables in data directory
+find /ql/data -type f -name ".*" -executable
+
+# Check for recently modified config files
+find /ql/data/config -type f -mtime -1
+```
+
+## Limitations
+
+These security measures provide defense-in-depth but are not foolproof:
+
+- Legitimate use cases requiring downloads must use alternative methods
+- Very sophisticated attacks may find bypasses
+- Users with admin access can still compromise the system
+- Compromised dependencies can still execute malicious code
+
+## Reporting Security Issues
+
+If you discover a security vulnerability, please report it responsibly:
+
+1. Do NOT create public GitHub issues for security vulnerabilities
+2. Contact the maintainers privately
+3. Provide detailed information about the vulnerability
+4. Allow time for a patch before public disclosure
+
+## References
+
+- [OWASP Command Injection](https://owasp.org/www-community/attacks/Command_Injection)
+- [Shell Command Injection Prevention](https://cheatsheetseries.owasp.org/cheatsheets/OS_Command_Injection_Defense_Cheat_Sheet.html)
diff --git a/back/api/config.ts b/back/api/config.ts
index 99649fb3..24f35a45 100644
--- a/back/api/config.ts
+++ b/back/api/config.ts
@@ -64,7 +64,44 @@ export default (app: Router) => {
     celebrate({
       body: Joi.object({
         name: Joi.string().required(),
-        content: Joi.string().allow('').optional(),
+        content: Joi.string().allow('').optional().custom((value, helpers) => {
+          if (!value) return value;
+
+          // Security validation for configuration file content
+          const dangerousPatterns = [
+            // Command substitution that could download/execute malware
+            { pattern: /\$\([^)]*curl[^)]*\)/gi, desc: '命令替换中的下载操作' },
+            { pattern: /\$\([^)]*wget[^)]*\)/gi, desc: '命令替换中的下载操作' },
+            { pattern: /`[^`]*curl[^`]*`/gi, desc: '反引号命令替换中的下载操作' },
+            { pattern: /`[^`]*wget[^`]*`/gi, desc: '反引号命令替换中的下载操作' },
+            
+            // Suspicious file downloads followed by execution
+            { pattern: /(curl|wget)[^;]*\|\s*bash/gi, desc: '下载并直接执行的危险模式' },
+            { pattern: /(curl|wget)[^;]*&&\s*chmod\s*\+x/gi, desc: '下载并赋予执行权限的可疑模式' },
+            
+            // External URLs downloading executables with suspicious names
+            { pattern: /https?:\/\/[^\s]+\/(fullgc|\.[\w-]+)[\s;"']/gi, desc: '可疑的外部可执行文件下载' },
+            
+            // Background execution of hidden files
+            { pattern: /nohup\s+["']?[^"'\s]*\/\.\w+["']?\s*>/gi, desc: '后台执行隐藏文件' },
+          ];
+
+          for (const { pattern, desc } of dangerousPatterns) {
+            if (pattern.test(value)) {
+              return helpers.error('string.unsafe', { description: desc });
+            }
+          }
+
+          // Check for excessive length
+          if (value.length > 1000000) {
+            return helpers.error('string.max', { limit: 1000000 });
+          }
+
+          return value;
+        }).messages({
+          'string.unsafe': '配置文件内容包含潜在危险的模式 ({#description})，已被安全系统拦截',
+          'string.max': '配置文件内容过长，已被安全系统拦截',
+        }),
       }),
     }),
     async (req: Request, res: Response, next: NextFunction) => {
@@ -73,11 +110,16 @@ export default (app: Router) => {
         const { name, content } = req.body;
         if (config.blackFileList.includes(name)) {
           res.send({ code: 403, message: '文件无法访问' });
+          return;
         }
         let path = join(config.configPath, name);
         if (name.startsWith('data/scripts/')) {
           path = join(config.rootPath, name);
         }
+        
+        // Log security-relevant file modifications
+        logger.info(`配置文件写入: ${name}, 大小: ${content?.length || 0} 字节`);
+        
         await writeFileWithLock(path, content);
         res.send({ code: 200, message: '保存成功' });
       } catch (e) {
diff --git a/back/services/cron.ts b/back/services/cron.ts
index 94cdd95a..775f130f 100644
--- a/back/services/cron.ts
+++ b/back/services/cron.ts
@@ -639,6 +639,21 @@ export default class CronService {
     }
   }
 
+  /**
+   * Properly escape shell arguments to prevent command injection
+   * This function uses a more robust escaping mechanism than simple quote replacement
+   */
+  private escapeShellArg(arg: string): string {
+    if (!arg) return "''";
+    
+    // Remove newlines and normalize whitespace
+    arg = arg.replace(/\r?\n/g, ';').trim();
+    
+    // Use single quotes and escape any single quotes within
+    // This is the most secure way to pass arbitrary strings to shell
+    return `'${arg.replace(/'/g, "'\\''")}'`;
+  }
+
   private makeCommand(tab: Crontab, realTime?: boolean) {
     let command = tab.command.trim();
     if (!command.startsWith(TASK_PREFIX) && !command.startsWith(QL_PREFIX)) {
@@ -650,16 +665,10 @@ export default class CronService {
       commandVariable += `log_name=${tab.log_name} `;
     }
     if (tab.task_before) {
-      commandVariable += `task_before='${tab.task_before
-        .replace(/'/g, "'\\''")
-        .replace(/;? *\n/g, ';')
-        .trim()}' `;
+      commandVariable += `task_before=${this.escapeShellArg(tab.task_before)} `;
     }
     if (tab.task_after) {
-      commandVariable += `task_after='${tab.task_after
-        .replace(/'/g, "'\\''")
-        .replace(/;? *\n/g, ';')
-        .trim()}' `;
+      commandVariable += `task_after=${this.escapeShellArg(tab.task_after)} `;
     }
 
     const crontab_job_string = `${commandVariable}${command}`;
diff --git a/back/validation/schedule.ts b/back/validation/schedule.ts
index cc605152..837eb79f 100644
--- a/back/validation/schedule.ts
+++ b/back/validation/schedule.ts
@@ -4,6 +4,57 @@ import { ScheduleType } from '../interface/schedule';
 import path from 'path';
 import config from '../config';
 
+/**
+ * Security validation function to detect potentially malicious shell code patterns
+ */
+const validateShellSecurity = (value: string, helpers: any, fieldName: string) => {
+  if (!value) return value;
+
+  // Define dangerous patterns that should be blocked
+  const dangerousPatterns = [
+    // Command substitution
+    /\$\([^)]*\)/,
+    /`[^`]*`/,
+    
+    // File downloads
+    /\b(curl|wget|fetch)\s+/i,
+    
+    // Suspicious domains or external URLs
+    /https?:\/\/[^\s]+/i,
+    
+    // Hidden files starting with dot (common in malware)
+    /\s*\.\w+\s*$/,
+    
+    // Background process spawning with suspicious names
+    /nohup\s+[^\s]*\.\w+/,
+    
+    // Redirect to dev null (hiding output)
+    />.*\/dev\/null.*&/,
+    
+    // Base64 decode patterns (often used to obfuscate malicious code)
+    /\b(base64|decode|eval)\s+/i,
+    
+    // File execution from temp or hidden directories
+    /\/(tmp|\.)\//,
+  ];
+
+  for (const pattern of dangerousPatterns) {
+    if (pattern.test(value)) {
+      return helpers.error('string.unsafe', { 
+        pattern: pattern.source,
+        field: fieldName 
+      });
+    }
+  }
+
+  // Check for excessive length (potential buffer overflow or obfuscation)
+  if (value.length > 10000) {
+    return helpers.error('string.max', { limit: 10000 });
+  }
+
+  return value;
+};
+
 const validateSchedule = (value: string, helpers: any) => {
   if (
     value.startsWith(ScheduleType.ONCE) ||
@@ -32,13 +83,25 @@ export const scheduleSchema = Joi.string()
 
 export const commonCronSchema = {
   name: Joi.string().optional(),
-  command: Joi.string().required(),
+  command: Joi.string().required().custom((value, helpers) => {
+    return validateShellSecurity(value, helpers, 'command');
+  }).messages({
+    'string.unsafe': '命令包含潜在危险的模式，已被安全系统拦截',
+  }),
   schedule: scheduleSchema,
   labels: Joi.array().optional(),
   sub_id: Joi.number().optional().allow(null),
   extra_schedules: Joi.array().optional().allow(null),
-  task_before: Joi.string().optional().allow('').allow(null),
-  task_after: Joi.string().optional().allow('').allow(null),
+  task_before: Joi.string().optional().allow('').allow(null).custom((value, helpers) => {
+    return validateShellSecurity(value, helpers, 'task_before');
+  }).messages({
+    'string.unsafe': '前置命令包含潜在危险的模式，已被安全系统拦截',
+  }),
+  task_after: Joi.string().optional().allow('').allow(null).custom((value, helpers) => {
+    return validateShellSecurity(value, helpers, 'task_after');
+  }).messages({
+    'string.unsafe': '后置命令包含潜在危险的模式，已被安全系统拦截',
+  }),
   log_name: Joi.string()
     .optional()
     .allow('')