Session IDs in URLs

Category: Protocol Vulnerabilities
Severity: Medium
MITRE ATT&CK Mapping: T1539 (Steal Web Session Cookie)

Description

Exposure of sensitive session identifiers in URL parameters, violating security best practices and enabling session hijacking through URL exposure.

Technical Details

Attack Vector

  • Session IDs in URL parameters
  • URL-based session exposure
  • Session token leakage
  • Referer header exposure

Common Techniques

  • URL parameter extraction
  • Log file analysis
  • Referer header harvesting
  • Browser history exploitation

Impact

  • Session Hijacking: Unauthorized access to user sessions
  • Session Exposure: Session tokens visible in logs and history
  • Privacy Violation: User sessions exposed to unauthorized parties
  • Authentication Bypass: Unauthorized access through exposed session IDs

Detection Methods

URL Analysis

  • Monitor URL patterns for session IDs
  • Analyze URL parameters
  • Detect session token exposure
  • Monitor URL logging

Session Monitoring

  • Track session ID usage
  • Monitor session exposure
  • Detect session hijacking
  • Analyze session patterns

Mitigation Strategies

Session Security

  • Use secure session management
  • Implement session cookies
  • Deploy session protection
  • Monitor session usage

URL Security

  • Avoid session IDs in URLs
  • Use POST requests for sensitive data
  • Implement URL filtering
  • Monitor URL patterns

Real-World Examples

Example 1: Session ID in URL Parameter

# Vulnerable URL with session ID
https://mcp-server.com/api/tools?session_id=abc123def456

# Secure alternative using cookie
https://mcp-server.com/api/tools
Cookie: session_id=abc123def456

Example 2: Session Exposure in Logs

# Web server logs expose session IDs
192.168.1.100 - - [15/Jan/2024:10:30:15] "GET /api/tools?session_id=abc123def456 HTTP/1.1" 200 1234

# Session ID now visible in server logs

Example 3: Referer Header Leakage

# User clicks external link, session ID leaked in referer
GET https://external-site.com/page
Referer: https://mcp-server.com/dashboard?session_id=abc123def456

# Session ID exposed to external site

References & Sources

  • Equixly - “MCP Servers: The New Security Nightmare”

Session IDs in URLs represent a fundamental security flaw that can lead to session hijacking and unauthorized access.