SS7 Attacks - The Exploit That Can Intercept Your Calls and Texts

 

In an era where cybersecurity threats are constantly evolving, one of the lesser-known but dangerous vulnerabilities in the global telecom infrastructure involves a protocol called Signaling System 7 (SS7). This system, crucial to how mobile networks communicate with each other, is vulnerable to attacks that allow hackers to intercept calls, read text messages, and track users’ locations. But what exactly is an SS7 attack, and why should you be concerned? Let’s dive into how this attack works and why it remains a significant threat today.

What is SS7?

SS7, or Signaling System 7, is a set of protocols used by telecommunication networks to exchange information necessary for setting up and routing phone calls, sending SMS messages, and enabling services like roaming between different networks. It acts as the backbone of global mobile communication, allowing different phone networks to communicate with each other efficiently.

SS7 was designed in the 1970s, at a time when security was not a major concern because it was assumed only trusted phone companies would have access to the system. However, as mobile communications have become more complex and widespread, the lack of strong security in SS7 has become a glaring weakness, leading to the rise of SS7-based attacks.

How SS7 Attacks Work: Step-by-Step

1. Gaining Access to the SS7 Network

The first step in executing an SS7 attack is gaining access to the SS7 network. This is the most challenging step but has become easier due to the widespread connectivity of telecom networks. Hackers may gain access by:

• Posing as legitimate telecom companies.
• Exploiting vulnerabilities in smaller, less secure mobile operators.
• Purchasing access on the dark web.

Once inside the network, attackers have the ability to send commands to the telecom systems and manipulate phone traffic.

2. Identifying the Target

With SS7 access, the hacker can now begin targeting specific phone numbers. The attacker simply needs the phone number of the victim they want to spy on. By sending specific SS7 commands to the network, the hacker can obtain information about the target, such as:

• Location: The attacker can track the victim’s location by requesting details from the mobile operator’s network. The system will return the location based on nearby cell towers.
• Status of the phone: The attacker can check whether the phone is active, connected to the network, or engaged in a call.

3. Intercepting Communications

The most dangerous part of an SS7 attack is the ability to intercept and redirect communications. Hackers can:

• Listen to calls: By using SS7 commands, the attacker can redirect the victim’s phone calls to a number they control, effectively allowing them to listen in on the conversation.
• Read SMS messages: The hacker can also intercept SMS messages, which is especially dangerous when it comes to two-factor authentication (2FA). Many online services, like banks and social media platforms, send one-time passwords (OTPs) via SMS. If an attacker intercepts this, they can gain unauthorized access to accounts.
• Manipulate the flow of communications: The attacker can reroute communications through their own device without the victim knowing. For instance, if someone calls the victim, the hacker can silently listen in or even block the call from reaching the victim altogether.

4. Tracking and Monitoring the Target

Even beyond intercepting calls and texts, attackers can use SS7 to continually track the victim’s location. By sending periodic location requests through the SS7 network, the hacker can follow the movements of the target in real-time. This is done silently, without alerting the victim or their mobile network operator.

5. Impersonating the Target

The ability to read SMS messages gives the hacker the power to impersonate the victim online. For example, if a hacker intercepts a two-factor authentication code from a bank or email service, they can log into the victim’s account and take control of it. Since many services use SMS-based authentication, this is a major concern.

Why SS7 is Still a Major Threat

One of the reasons SS7 attacks are so dangerous is because the victim remains completely unaware. Unlike other hacking methods that might involve malware or phishing emails, SS7 attacks occur within the telecom infrastructure itself, making it invisible to the user.

Moreover, despite the known vulnerabilities in SS7, it’s difficult for mobile operators to overhaul or replace the system. SS7 is deeply embedded in the global telecom infrastructure, and making changes to such a fundamental system is costly and complex. As a result, SS7 vulnerabilities continue to pose a significant security risk to millions of mobile users worldwide.

Real-World Impact

Several high-profile SS7 attacks have occurred in recent years. In 2017, hackers reportedly exploited SS7 to steal money from bank accounts by intercepting SMS codes sent to customers for online banking verification. Other attacks have targeted political figures, business executives, and journalists, allowing attackers to track their movements and monitor sensitive conversations.

How to Protect Yourself from SS7 Attacks

While individual users can’t directly fix SS7 vulnerabilities, there are steps you can take to minimize the risk:

1. Avoid SMS-based two-factor authentication (2FA): Use app-based authentication methods like Google Authenticator or Authy instead of relying on SMS for 2FA codes.
2. Use encrypted messaging apps: Applications like Signal and WhatsApp offer end-to-end encryption, making it harder for hackers to intercept your messages, even if they have SS7 access.
3. Be cautious with sensitive information: Avoid sharing sensitive information over phone calls or SMS, especially if you’re discussing financial or personal matters.

Conclusion

The SS7 attack is a stark reminder of the vulnerabilities that exist in the infrastructure we rely on daily. While it may seem like a relic of the past, the SS7 protocol remains in use globally, and its weaknesses continue to be exploited by attackers. As mobile users, being aware of these risks and taking steps to protect your communications is crucial in an age where privacy is constantly under threat. Until telecom companies implement more secure systems, SS7 attacks will likely remain a potent weapon in the hands of hackers.

**Rodgers Munene**​​