Modern VoIP and SIP networks are strong, agile, and cost-effective, but they are increasingly targeted by advanced threat actors. Below are ten major security risks to watch in 2025, along with practical ways to reduce exposure and stay protected.
1. Open or Uncovered SIP Ports (especially 5060 / 5061)
Risk:
SIP signaling typically runs over ports 5060 (UDP/TCP) and 5061 (TLS). If these ports are exposed to the public internet without proper restrictions, they become prime targets for automated scans, brute-force attacks, flooding, or exploitation. Attackers continuously look for open SIP services to gather information or find vulnerabilities.
How to Protect:
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Pass SIP traffic through firewall rules for trusted IPs
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Use Session Border Controllers (SBCs) to hide internal topology
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Throttle message rates
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Consider moving signaling to non-standard ports when possible
2. Weak or Default Credentials
Risk:
Many SIP endpoints and PBXs still use default usernames and weak passwords, leaving systems vulnerable to credential stuffing and brute-force attacks. Once compromised, attackers can reroute calls or move laterally within your network.
How to Protect:
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Change default credentials immediately
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Enforce strong passwords
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Use Multi-Factor Authentication (MFA) for admin access
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Limit login attempts
3. Lack of SIP & RTP Encryption
Risk:
Unencrypted SIP signaling or RTP media can allow attackers to intercept call data, credentials, or voice/video content, enabling eavesdropping or impersonation.
How to Protect:
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Use TLS for signaling
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Use SRTP for media
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Enforce strong cryptography like AES-GCM
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Confirm your provider supports encryption by default
4. Toll Fraud & International Call Exploits
Risk:
Attackers who gain access to your PBX can make high-cost or international calls, generating massive bills. Traffic pumping can also route unwanted calls through your system.
How to Protect:
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Restrict dialing rules
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Disable unused features
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Monitor call records for unusual activity
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Use fraud detection tools
5. SIP Spoofing & Caller ID Manipulation
Risk:
Attackers can forge SIP headers to make calls appear legitimate, facilitating phishing and social engineering attacks.
How to Protect:
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Deploy STIR/SHAKEN or similar frameworks
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Validate and rewrite headers using SBCs
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Screen incoming calls for suspicious identities
6. SIP Registration Hijacking
Risk:
Registration hijacking occurs when attackers take control of a SIP registration, redirecting inbound and outbound calls for eavesdropping or misuse.
How to Protect:
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Use secure authentication methods
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Reduce registration intervals
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Whitelist known endpoints
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Monitor registration logs for anomalies
7. Denial-of-Service (DoS) & SIP Flooding
Risk:
DoS attacks overwhelm SIP servers with excessive requests or malformed messages, causing call failures or system crashes.
How to Protect:
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Apply rate-limiting
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Use SBCs to filter malformed messages
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Segment your voice infrastructure
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Keep SIP/PBX software updated
8. Weakly Secured Endpoints
Risk:
IP phones, softphones, and VoIP apps often lack proper security controls, leaving them vulnerable to malware or unauthorized access.
How to Protect:
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Keep firmware updated
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Disable unnecessary services
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Enforce encryption
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Monitor endpoint behavior
9. Incorrect Trunk Configurations & Routing Logic
Risk:
Misconfigured trunks, permissive dial plans, or lax routing rules can be exploited for unauthorized calls.
How to Protect:
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Regularly review trunks, dial plans, and ACLs
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Disable unused features
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Use expert evaluation when needed
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Employ an SBC for normalization and control
10. Lack of Monitoring & Incident Detection
Risk:
Without logging, monitoring, and alerts, attacks can go unnoticed for long periods, increasing damage and compliance risks.
How to Protect:
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Centralize logs in a SIEM or analytics platform
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Establish baseline behaviors
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Create anomaly-based alerts
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Test your incident response plan
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Automate remediation where possible
Other Emerging Risks (2025)
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SIMBox bypass fraud
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Side-channel traffic profiling
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AI-driven attacks
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Software vulnerabilities
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Multi-hop encryption gaps
Not sure where to start with securing your VoIP or SIP system?
Don’t worry, you don’t have to figure it out alone. Our team of experts can help you assess your current setup, identify risks, and implement the right protections for your business. Contact Us or call us at +1 305-256-2024.
