New Brazilian Banking Trojan Targets Mobile Users in Multiple Countries

A Brazil-based threat group that recently has been expanding its operations worldwide has deployed a new banking Trojan that is actively targeting Android users in multiple Latin American and European countries and could soon hit US users as well.

Researchers at Kaspersky recently discovered the so-called "Ghimob" remote access Trojan (RAT) while investigating another malware campaign. In a report this week, the security vendor described the malware as arriving on mobile devices via email purporting to be about some kind of debt.

Recipients who fall for the scam and click on an embedded link in the email end up downloading the RAT on their devices. Once installed, Ghimob is capable of a variety of malicious actions that start with sending a message about successful infection to an attacker-controlled server.

The initial message includes data on phone model, a list of all applications on the device, and information on whether the user has implemented lock-screen security.

The Trojan, like a lot of Android malware, prompts users to grant it full access rights on the compromised device. Fabio Assolini, security researcher at Kaspersky, says that Ghimob, once installed, gives attackers complete remote control of the device. They can use it to take screenshots, use the microphone, and record all text typed in online fields and in mobile apps.

The Trojan can spy on 153 mobile apps, prevent manual uninstallation, install other apps from any source, and control the apps already installed — for instance, closing or opening an app or putting it in the background, Assolini says. "As the malware can take screenshots and act as a keylogger, any password typed or touched in the screen can be captured," he notes.

Ghimob can also record and replace any lock-screen pattern the user might have implemented to secure access to the device. Also, for fingerprint-based biometric authentication, the malware can put a black screen on the phone. "When the user tries to unlock the screen — using his fingerprint — the Trojan is using it to unlock any other financial app installed, tricking the user [into doing] it with his own fingerprint," Assolini says.

Because the malware uses the victim's own device to execute its fraudulent actions, most anti-fraud mechanisms at banks and other financial institutions trust the access and tend to accept the actions as legitimate, he says. In addition to bank accounts, Ghimob also targets apps from financial services companies, exchanges, and cryptocurrencies.

Brazilian Threat Actor
Kaspersky identified the group behind the malware as Guildma, a Brazilian threat actor associated with a set of four major banking Trojan families collectively referred to as the Tetrade. Until recently, the group has focused mostly on mobile device users in Brazil. But recently, it began aggressively expanding its operations and currently poses a threat to mobile banking users in multiple countries, including Angola, Germany, Mozambique, Paraguay, Peru, and Portugal, according to Kaspersky.

Assolini says it's unclear if Ghimob has targeted users in North America. But the malware is ready to steal data from multiple applications, including international payment systems in North America and other regions. "The Trojan is ready to steal credentials from several users," he says. "All it needs is the desire of the criminal, as addition of new targets in the malware seems pretty easy."

News of the Guildma group's apparent plans to target users around the world with its new mobile malware tool fits into a broader pattern. As smartphone use has increased, the devices have become attractive targets for attackers. Though the mobile device environment remains somewhat harder to crack than PCs and notebooks, attackers have ramped up campaigns targeting smartphones and tablets anyway.

Thirty-nine percent of organization's surveyed for Verizon's Mobile Security Index said they had experienced a mobile device-related security incident — many of them major — over the previous 12 months. Malware is a growing problem, but so too is adware and other potentially harmful applications.