A growing menace: flubots, phishing, and network failures

As we buy more and more stuff online, text messages like "track your order at this link: http://…." are accepted as the norm. You've probably clicked one or two of those links yourself, right? And why shouldn't you?

It sounds innocent enough, but it might not be. That simple SMS could be the vehicle for a flubot attack. Clicking on the link could cause massive headaches for mobile operators and the industry as a whole. Increases in mobile malware pose a real threat to the telecommunications infrastructure. The implications are serious - both operationally and commercially.

How does a flubot work?

Successful flubots typically build-out botnets that can cripple telecoms networks by generating large volumes of voice calls and SMS messages, as well as mobile data traffic targeted at specific websites and servers - a DDOS (distributed denial-of-service) attack.

Flubots work like this: distribution systems send personalized SMS messages containing links that look genuine, making them difficult to detect and prevent. Clicking on the link triggers a malware download which can then take over the device and send a similar message to contacts; while also initiating DDOS attacks. The malware can also start phishing for bank details, perform identity theft, or make purchases.

How much damage can a flubot cause?

Flubot attacks are happening at scale. In October 21 alone, Sinch's anti-spam platform detected and blocked more than 1.6 million malicious URLs, while one mobile operator recently reported 10,000 customers had been infected by flubot malware. That attack generated 3,000 messages (both national and international) per customer per day, causing SMS traffic between network operators to soar tenfold. In another attack, 5,000 infected devices called a target number every 10 minutes, resulting in about 30,000 calls per hour.

In the graphic below, you can see the evolution of a flubot attack on a medium-sized MNO in the APAC region. Sinch anti-fraud systems captured over 100K fraudulent SMS messages before customers realized anything had happened. This case is very similar to others seen around that time.

The attack began with an SMS notification for a package delivery, but the content changed as the attack gained ground. Typically, those who start a flubot attack will change the content of the messages and even deliberately misspell words to avoid detection.

In some cases, the SMS claim to include links to photos sent by friends, vaccine appointments, and even COVID-19 test results. At the height of the attack, Sinch blocked up to 30,000 flubot attacks a day on the APAC operator's network.

What happens when a flubot is successful?

When an attack succeeds, interconnection gateways can quickly become overloaded, and elements of the operator's core network can be overwhelmed. Regular traffic is displaced, calls can't get through, and messages go undelivered.

For individual consumers, a flubot attack can result in a loss of privacy. The malware could hack into the handset's camera, track the device's location, record phone calls, access personal data, monitor internet usage, and even use one-time passwords to open bank accounts and online payment services, including direct carrier billing.

Once it has taken over the phone, the malware could click on advertising banners to boost revenue for a specific publisher, use the handset's computing power and energy for crypto-mining, or use any app on the phone - camera, audio, and social media included.

What's behind this latest wave of flubot attacks?

So why has there been a wave of flubot attacks recently? The main reason is data breaches at leading social networks, such as Facebook and LinkedIn. Some 533 million Facebook user phone numbers and personal data were leaked online. The data belongs to people across 106 countries, including over 32 million records on users in the U.S., 11 million users in the UK, and 6 million users in India. Leaked records included their phone numbers, Facebook IDs, full names, locations, birthdates, bios, and, in some cases, email addresses.

Some 500 million LinkedIn users have also been the victims of a data breach, exposing LinkedIn IDs, full names, email addresses, phone numbers, and genders. Of course, it isn't just these Facebook and LinkedIn users that are vulnerable. When a flubot successfully attacks a phone, it can then steal data from the address books of infected devices, to continue spreading malware.

Governments around the world have started warning consumers about the threat of flubots. But telecoms operators also need to shore up their defences to put a stop to these attacks.

So, what can you do? In our next blog post we'll outline the best measures operators can take to counter the flubot menace - don't miss it!

Find out how SMS Transformation can help in the fight against flubots and discover how reliable and safe SMS can be when it's done right!