Sandbox Escape

Category: Privilege & Access Control
Severity: Critical
MITRE ATT&CK Mapping: T1055 (Process Injection)

Description

Breaking out of security sandboxes and containment mechanisms designed to isolate MCP tools and processes, enabling access to the broader system environment.

Technical Details

Attack Vector

  • Sandbox implementation flaws
  • Containment bypass techniques
  • Security boundary violations
  • Isolation mechanism failures

Common Techniques

  • Container escape techniques
  • Virtual machine breakout
  • Process isolation bypass
  • Security boundary violations

Impact

  • System Access: Breaking out of containment to access host system
  • Security Bypass: Circumventing security isolation mechanisms
  • Lateral Movement: Accessing systems outside the sandbox
  • Privilege Escalation: Gaining higher privileges outside containment

Detection Methods

Sandbox Monitoring

  • Monitor sandbox integrity
  • Detect escape attempts
  • Track containment violations
  • Analyze sandbox behavior

System Monitoring

  • Monitor system activities
  • Track process behavior
  • Detect privilege escalation
  • Analyze system integrity

Mitigation Strategies

Sandbox Security

  • Harden sandbox implementations
  • Implement strong isolation
  • Deploy escape detection
  • Regular security updates

Containment Controls

  • Implement multi-layered containment
  • Use secure isolation mechanisms
  • Deploy monitoring systems
  • Regular security audits

Real-World Examples

Example 1: Container Escape via Mount Points

# Vulnerable container configuration
import os
import subprocess

def execute_in_container(command):
    # Weak container isolation
    container_config = {
        "mounts": [
            {"source": "/", "target": "/host", "type": "bind"}
        ]
    }
    
    # Attacker escapes via host mount
    # command = "chroot /host /bin/bash"
    subprocess.run(["docker", "run", "--privileged", "-v", "/:/host", "image", command])

Example 2: Process Namespace Escape

# Vulnerable process isolation
import os

def create_sandbox():
    # Weak process isolation
    pid = os.fork()
    
    if pid == 0:
        # Child process in "sandbox"
        # Insufficient namespace isolation
        os.execv("/bin/sh", ["sh"])
    else:
        # Parent process
        os.waitpid(pid, 0)
    
    # Attacker breaks out of weak isolation
    # Access to parent process namespace

Example 3: File System Escape

# Vulnerable file system containment
import os

class SandboxFileSystem:
    def __init__(self):
        self.jail_dir = "/tmp/sandbox"
        
    def access_file(self, path):
        # Insufficient path validation
        full_path = os.path.join(self.jail_dir, path)
        
        # Vulnerable to path traversal
        if os.path.exists(full_path):
            return open(full_path, 'r').read()
        
        # Attacker escapes sandbox
        # path = "../../../../etc/passwd"

References & Sources

  • Academic Paper - “Model Context Protocol (MCP): Landscape, Security Threats, and Future Research Directions”
  • Strobes Security - “MCP and Its Critical Vulnerabilities”

Sandbox escape represents a critical security vulnerability that can completely compromise the isolation and containment of MCP systems.