HTTP Injector Steals Mobile Internet Access

A new attack in the wild leans not on email nor ransom, but on YouTube, Telegram, and HTTP headers intended to confuse an ISP.

Researchers at Flashpoint found that hackers have developed HTTP injectors that gain them free Internet access on mobile phone networks — and that they're trading these injectors like cents-off coupons at a neighborhood swap meet.

The most striking aspects of the attacks, which Flashpoint tracked on mobile networks in South America, the method of transmittal and ubiquity, not sophistication. 

Liv Rowley, an intelligence analyst at Flashpoint, says that Spanish and Portuguese chatter on Telegram first alerted her that something unusual was going on. "I was seeing all these people exchanging these HTTP inductor files, saying that you can get free Internet with them," she says.

In the attacks, customers with pre-paid SIMs employ the HTTP injectors to confuse the captive portals carriers use to verify the balance on the SIM before allowing access to the network. With the portal confused, the user gets onto the Internet even when the balance on the SIM has dropped to zero. The current attack primarily targets carriers in Brazil and Colombia, though Flashpoint found evidence of the same mechanisms being used elsewhere.

"You can very easily find YouTube videos all sorts of languages from all different countries where people explain how these files are used, and they often will include a download link to one of these injector files as well," Rowley says.

The openness of the information suggests a couple of factors to Rowley. First, she says, there's not a huge risk for the users in getting caught. "A hallmark of Latin American cybercrime right now is that there's not a lot of cybercrime legislation," Rowley says, pointing out that individuals can often commit cybercrime and there's no legal infrastructure in place to actually penalize them.

Next, the cybercriminals Flashpoint believes are behind the injectors gain access to the compromised infrastructure. Rowley says that it's in their best interest to have a lot of other people using these techniques to create a bigger criminal "bait ball" in which the true criminals can get lost.

The creation and distribution of these HTTP injectors makes them unique, in Rowley's view. "It's an interesting ecosystem of people who are compromising infrastructure trickling down to people who are just getting something that they're essentially being handed," she says. The flow of the malware from technologically sophisticated creators to technologically unsophisticated willing users is unusual, and dangerous.

While this exploit certainly has a significant financial impact on the mobile carriers, Rowley sees the potential for greater harm in the future. The originating criminals are "exploiting other people who aren't going to look critically at the files that they're downloading or the apps that they're downloading," she says. "The potential is always going to be there for them to be exploiting somebody downstream."

And the next payload, which could include anything from recruitment into a botnet to a cryptojacker, may have fewer benefits to the user and many more dangers for the Internet at large, according to Flashpoint.

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