SS7 Attacks: Intercepting Mobile Traffic

TL;DR

Yes, attackers can intercept mobile traffic using vulnerabilities in the Signaling System No. 7 (SS7) protocol. This is a serious cyber security risk because SS7 is used by almost all mobile networks worldwide to handle calls and texts. While directly exploiting it requires significant resources, it’s possible through access to network infrastructure or purchasing services from rogue providers.

What is SS7?

SS7 is the set of protocols that allows mobile phone companies to exchange information needed to route your calls, send texts, and enable roaming. It’s been around for decades and wasn’t designed with modern security in mind. Think of it as the plumbing behind all mobile communication.

How can an attacker intercept traffic?

1. Access to Network Infrastructure: The most direct way is gaining access to a mobile network operator’s (MNO) SS7 infrastructure. This is extremely difficult and usually involves sophisticated hacking or insider threats.
2. Rogue Providers: Attackers can purchase services from smaller, less secure providers who have access to the SS7 network. These providers may not adequately vet their customers.
3. Exploiting Vulnerabilities: Specific vulnerabilities within SS7 allow attackers to:
   • Location Tracking: Request a mobile phone’s current location.
   • Call Detail Record (CDR) Interception: Obtain records of calls made and received, including timestamps and numbers involved.
   • SMS Interception: Read text messages sent and received by the target.
   • Denial of Service: Disrupt mobile services for a specific user or area.

Steps an attacker might take

1. Reconnaissance: Identify the target’s mobile network operator (MNO).
2. Access Acquisition: Obtain access to SS7 infrastructure, either directly or through a rogue provider. This often involves setting up accounts with SMS gateways or signalling platforms.
3. Signalling Message Injection: Send malicious SS7 messages to the network. For example, to request location information:

   MAP-Request Location Notification

4. Data Collection: Collect intercepted data (location, CDRs, SMS content).
5. Analysis & Exploitation: Analyze the collected data for valuable information or use it for malicious purposes.

How to protect yourself

1. End-to-End Encryption: Use messaging apps that offer end-to-end encryption (e.g., Signal, WhatsApp). This protects the content of your messages even if they are intercepted.
2. VPNs: While a VPN doesn’t directly protect against SS7 attacks, it can add an extra layer of security by encrypting your internet traffic.
3. Be Aware of Phishing: Avoid clicking on suspicious links or providing personal information to untrusted sources. Attackers may use phishing to gain access to your accounts.
4. Monitor Your Account: Regularly check your mobile account for unusual activity, such as unexpected charges or roaming data usage.
5. Use Strong Authentication: Enable two-factor authentication (2FA) on all of your important accounts.

Mitigation by Mobile Network Operators

1. SS7 Firewalling: Implement firewalls to filter out malicious SS7 messages.
2. Traffic Analysis: Monitor SS7 traffic for anomalies and suspicious patterns.
3. Security Audits: Regularly audit their SS7 infrastructure for vulnerabilities.
4. Collaboration & Information Sharing: Share threat intelligence with other operators to improve cyber security defenses.