WannaLocker, a mobile lookalike of the infamous WannaCry ransomware, just got a little more dangerous.
Researchers at Avast this week reported observing a new version of the malware that combines WannaCry's user interface with new spyware, a banking Trojan, and remote administration functions.
The three-pronged threat, which the security vendor calls WannaHydra, is currently targeting users of four major banks in Brazil. But if it takes off, the malware could prove to be a major issue for Android users everywhere, Avast said.
WannaLocker surfaced in June 2017 around the same time as WannaCry. Avast first observed it targeting users of Chinese gaming forums disguised as a plug-in for a popular game.
When installed, the malware encrypted certain files stored on the device's external storage while leaving other files untouched, including files smaller than 10KB in size and files containing "DCIM" or "download" in its path, Avast noted at the time. It then demanded a ransom of 40 Renminbi (currently around $5.80) for the decryption key. Trend Micro described the malware as a variant of SLocker, one of the earliest known ransomware tools, with a copycat GUI of WannaCry.
The latest version of WannaLocker works by presenting users of the four targeted bank apps with a fake message urging them to sign into their accounts to address some account-related issue. Once installed, the malware collects a variety of information including the name of the device manufacturer and other hardware information, the phone number, text messages, call log, photos, contact list, microphone audio data, and GPS location information.
Like previous strains, the latest version of WannaLocker has the capability to encrypt files on the infected Android device's external storage. But that particular feature appears to be still a work in progress, Avast said.
"The new malware, WannaHydra, shares the same UI [as WannaCry] in its ransomware module, but contains more capabilities including spyware and a banking Trojan," says Nikolaos Chrysaidos, mobile threat researcher at Avast.
"It has quite wide-ranging abilities to collect information and could be used to extract personal and financial information in addition to delivering the ransomware package," he says. It's unclear, though, how much money, if any, the attackers might be asking as ransom, he notes.
WannaHydra appears to be still in development, so additional features could be added or some of it removed at a later date, he adds. Such mobile malware typically poses more of a threat to Android users because attackers continue to find it easier to deliver malicious code on Android than on iOS devices, he says.
"In this instance, the attack is targeted toward users in Brazil, but anyone can be a victim of mobile malware," he cautions. That is why it is important for Android users to only download apps from trusted developers on certified app stores like Google Play.
Sam Bakken, senior product marketing manager at cybersecurity vendor OneSpan, says it is quite likely that the ransomware functionality in the new WannaLocker variant itself exists as a fallback option in situations where an infected device might not have installed the app of one of the four targeted banks. "It would then fall back to the ransomware attack," in these situations, he says.
Android users should ensure they are on the most up-to-date version of the operating system as possible, Bakken notes. Often that can be difficult because Android users are often tied to the OS upgrade schedules of their device manufacturer or cellphone service providers, he says.
In addition, even when downloading apps from Google's official store, users should make sure to check the number of downloads the app has and pay special attention to negative reviews, Bakken advises.
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