VoIP Platform Risk Assessment

VoIP Risk Assessment Framework

A structured risk assessment evaluates your VoIP environment across multiple domains. This framework provides comprehensive coverage while remaining practical for organizations of any size.

Assessment Domains

Risk Scoring Methodology

Score each finding based on impact and likelihood:

class VoIPRiskScoring:
    """
    Risk scoring for VoIP assessment findings.
    """
    IMPACT_SCORES = {
        'critical': 5,   # Service outage, major fraud, data breach
        'high': 4,       # Significant financial loss, targeted attack
        'medium': 3,     # Moderate impact, exploitable vulnerability
        'low': 2,        # Minor impact, defense-in-depth issue
        'informational': 1  # Best practice, minimal risk
    }

    LIKELIHOOD_SCORES = {
        'almost_certain': 5,  # Active exploitation seen
        'likely': 4,          # Easy to exploit, common attack
        'possible': 3,        # Requires skill/access
        'unlikely': 2,        # Complex attack chain needed
        'rare': 1             # Theoretical, highly unlikely
    }

    def calculate_risk(self, impact, likelihood):
        """Risk = Impact x Likelihood (1-25 scale)"""
        score = self.IMPACT_SCORES[impact] * self.LIKELIHOOD_SCORES[likelihood]

        if score >= 20:
            priority = 'critical'
        elif score >= 12:
            priority = 'high'
        elif score >= 6:
            priority = 'medium'
        else:
            priority = 'low'

        return {
            'score': score,
            'priority': priority,
            'remediation_timeline': self._get_timeline(priority)
        }

    def _get_timeline(self, priority):
        timelines = {
            'critical': 'Immediate (24-48 hours)',
            'high': '1-2 weeks',
            'medium': '30-60 days',
            'low': '90 days or next maintenance window'
        }
        return timelines[priority]

Infrastructure Security Assessment

Network Architecture Review

Evaluate network design and segmentation:

SIP Endpoint Scanning

Use automated tools to identify SIP vulnerabilities:

# SIP endpoint discovery and enumeration
# Using SIPVicious for assessment (authorized testing only)

# Discover SIP endpoints
svmap 192.168.1.0/24 -p 5060-5061

# Enumerate extensions
svwar -e100-999 192.168.1.100 -m INVITE

# Test for common vulnerabilities
# - Default credentials
# - Anonymous registration
# - Call initiation without auth

# Asterisk-specific security scan
nmap -sV -p 5060,5061,8088,8089 192.168.1.100 \
  --script sip-methods,sip-enum-users

Infrastructure Findings Template

# Example assessment finding
{
    "id": "VOIP-INFRA-001",
    "title": "SIP Port Exposed to Internet",
    "domain": "Infrastructure",
    "description": "UDP port 5060 is accessible from any internet IP address.",
    "evidence": "nmap scan from external IP shows port 5060 open",
    "impact": "critical",
    "likelihood": "almost_certain",
    "risk_score": 25,
    "remediation": {
        "immediate": "Configure firewall to restrict SIP to carrier IPs only",
        "long_term": "Deploy SBC to handle external SIP connectivity"
    },
    "references": [
        "NIST SP 800-58: Security Considerations for VoIP Systems",
        "OWASP VoIP Security Testing Guide"
    ]
}

Authentication and Access Control

SIP Authentication Review

Password Audit

# Audit SIP credential strength
# Check for weak/default passwords in configuration

import re
from zxcvbn import zxcvbn  # Password strength library

def audit_sip_credentials(config_file):
    weak_credentials = []

    # Parse SIP peer configurations
    peers = parse_sip_config(config_file)

    for peer in peers:
        username = peer.get('username')
        secret = peer.get('secret')

        # Check password strength
        result = zxcvbn(secret)

        if result['score'] < 3:  # Score 0-4, 3+ is strong
            weak_credentials.append({
                'peer': peer['name'],
                'username': username,
                'score': result['score'],
                'feedback': result['feedback'],
                'crack_time': result['crack_times_display']['offline_slow_hashing_1e4_per_second']
            })

        # Check for common patterns
        if is_common_password(secret):
            weak_credentials.append({
                'peer': peer['name'],
                'issue': 'common_password',
                'recommendation': 'Use randomly generated password'
            })

    return weak_credentials

Encryption Assessment

Transport Security Review

TLS Configuration Testing

# Test TLS configuration
# Using testssl.sh for comprehensive analysis

# Test SIP TLS endpoint
testssl --starttls sip sip.example.com:5061

# Check for specific vulnerabilities
testssl --vulnerable sip.example.com:5061

# Verify cipher strength
nmap --script ssl-enum-ciphers -p 5061 sip.example.com

# Expected output should show:
# - TLS 1.2 or 1.3 only
# - No SSL 2/3 or TLS 1.0/1.1
# - Strong ciphers (ECDHE, AES-GCM)
# - No export ciphers, RC4, 3DES

Monitoring and Detection

Logging Review

Detection Gap Analysis

class DetectionGapAnalysis:
    """
    Identify gaps in fraud and attack detection.
    """
    REQUIRED_DETECTIONS = {
        'toll_fraud': {
            'description': 'Detect unauthorized international/premium calls',
            'indicators': [
                'international_call_volume_spike',
                'premium_rate_calls',
                'after_hours_international',
                'high_cost_destination_calls'
            ],
            'criticality': 'critical'
        },
        'credential_attack': {
            'description': 'Detect brute force and credential stuffing',
            'indicators': [
                'failed_auth_spike',
                'auth_from_new_ip',
                'credential_spray_pattern',
                'dictionary_attack_pattern'
            ],
            'criticality': 'high'
        },
        'account_takeover': {
            'description': 'Detect compromised accounts',
            'indicators': [
                'impossible_travel',
                'device_change',
                'behavior_anomaly',
                'privilege_escalation'
            ],
            'criticality': 'high'
        },
        'service_abuse': {
            'description': 'Detect spam/phishing via platform',
            'indicators': [
                'high_volume_outbound',
                'sequential_dialing',
                'spam_complaints',
                'short_call_duration_pattern'
            ],
            'criticality': 'medium'
        }
    }

    def assess_coverage(self, current_detections):
        gaps = []

        for threat, requirements in self.REQUIRED_DETECTIONS.items():
            missing = []
            for indicator in requirements['indicators']:
                if indicator not in current_detections:
                    missing.append(indicator)

            if missing:
                gaps.append({
                    'threat': threat,
                    'criticality': requirements['criticality'],
                    'missing_detections': missing,
                    'coverage_percentage': (
                        (len(requirements['indicators']) - len(missing)) /
                        len(requirements['indicators']) * 100
                    )
                })

        return sorted(gaps, key=lambda x: x['criticality'])

Operational Security Assessment

Policy and Procedures

Vendor Risk Assessment

# Vendor security questionnaire areas
VENDOR_ASSESSMENT_AREAS = {
    'infrastructure': [
        'Data center certifications (SOC 2, ISO 27001)',
        'Network redundancy and failover',
        'DDoS protection capabilities',
        'Encryption in transit and at rest'
    ],
    'access_control': [
        'Multi-tenant isolation',
        'Customer data segregation',
        'Admin access logging',
        'Background checks for staff'
    ],
    'fraud_protection': [
        'Toll fraud detection capabilities',
        'Spending limits and alerts',
        'Geographic restrictions',
        'Real-time CDR access'
    ],
    'compliance': [
        'STIR/SHAKEN attestation',
        'HIPAA support (if needed)',
        'PCI DSS compliance (if processing payments)',
        'Data retention policies'
    ],
    'incident_response': [
        'SLA for security incidents',
        'Breach notification timeline',
        'Fraud liability policies',
        'Support availability (24/7)'
    ]
}

Assessment Report Template

Executive Summary

Provide high-level overview for leadership:

# Executive summary template
EXECUTIVE_SUMMARY = """
## VoIP Security Assessment - Executive Summary

**Assessment Date:** {date}
**Scope:** {scope_description}
**Overall Risk Rating:** {overall_rating}

### Key Findings
- **Critical Issues:** {critical_count}
- **High Issues:** {high_count}
- **Medium Issues:** {medium_count}
- **Low Issues:** {low_count}

### Top Risks
1. {top_risk_1}
2. {top_risk_2}
3. {top_risk_3}

### Immediate Actions Required
{immediate_actions}

### Estimated Remediation Timeline
- Critical issues: {critical_timeline}
- High issues: {high_timeline}
- Full remediation: {full_timeline}
"""

Detailed Findings Format

# Detailed finding template
FINDING_TEMPLATE = """
## Finding: {finding_id}

**Title:** {title}
**Severity:** {severity}
**Domain:** {domain}
**Status:** {status}

### Description
{description}

### Evidence
{evidence}

### Business Impact
{business_impact}

### Technical Impact
{technical_impact}

### Remediation
#### Immediate
{immediate_remediation}

#### Long-term
{longterm_remediation}

### References
{references}

### Verification
{verification_steps}
"""

Remediation Prioritization

Priority Matrix

Quick Wins

High-impact, low-effort improvements:

1. Enable Fail2Ban — Immediate brute force protection
2. Block premium rate — Eliminate largest toll fraud vector
3. Enable TLS — Configuration change, no new infrastructure
4. Reset default passwords — Often missed, easy to fix
5. Enable MFA for admins — Highest-impact access protection

Complete Assessment Checklist

Ongoing Assessment Program

Security assessment should be continuous, not one-time: