Securing VoIP and PSTN from Integrated Signaling Network Vulnerabilities

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Securing VoIP and PSTN from Integrated Signaling
Network Vulnerabilities

• Hemant Sengar, George Mason University
• Ram Dantu, University of North Texas
• Duminda Wijesekera, George Mason University

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Background
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Integration of Voice and Data Network
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Public Switched Telephone Network
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SS7 Protocol Stack
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Integrated IP and SS7 Network

• Interconnect IP Network to SS7 Network

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SIGTRAN Protocol Suite
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M2PA in Signaling Transport
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SS7 Network Security Threats

• Telecommunication Deregulation Act,1996 has
  opened up market
• SS7 design and development carried out in
  different environment from the presently existing
  one.
• Convergence of voice and data networks

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IP Network Security Threats

• Denial of Service (DoS) attacks
• Spoofing, Sniffing.
• Viruses, Worms etc.
• Intrusion

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Marriage of SS7 and IP

• Exponential growth of IP Telephony
• More ISPs attach to SS7 Network
• Threats to Signaling Nodes
• May come from SS7 side
• or from IP side

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Signaling Nodes are Exposed

• Potential Threats due to Message Content
• ISUPs IAM message populated with Multilevel
  Precedence and Preemption (MLPP) parameter
• Populating CIC of IAM with 0000 value
• Caller ID may be spoofed
• Contd

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Signaling Nodes are Exposed

• MGC is used to bridge SIP and ISUP network
• Translation of ISUP to SIP and mapping of ISUP
  parameters into SIP headers
• Blind interpretation

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Signaling Nodes are Exposed

• Traffic Flow Analysis
• Traffic nature, load, network topology
• Subscribers behavior and identity
• Link Status Messages in IP Network
• Processor Outage
• Busy
• Out of Service

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Signaling Nodes are Exposed

• Misbehaving Node
• M2PA based IPSPs have two identifiers
• Violation of Protocol State Machine
• Continuous Proving
• Sequence of exchanged messages

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Current Status

• IP Network Side
• Signaling Nodes may use
• SSL
• or IPSec

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Secure Signaling Architecture
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Secure Signaling Architecture
Trust Management
Authentication
Gateway Screening (Firewall)
Intrusion Detection
Armor
DoS/Vulnerabilities
Signatures
Rule Changes
Re-Authentication
Trust Negotiation
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Trust Management

• Define Service Level Agreements
• Define Access control Policy

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Authentication

• IETF has proposed IPSec for IP Network
• Our Proposal of MTPSec for SS7 Network

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Proposed Solution

• Security Across MTP3 Layer
• Combination of two protocol
• Key Exchange (KE) Protocol
• Authentication Header (AH) Protocol

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Authentication Header Format
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Conclusion

• Provides Integrity and Authentication solution to
  all signaling nodes
• Enforces SLA and ACL policy at the interface
• Put checks on misbehaving entities

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Thank You !