As part of a fresh campaign that began in May 2021, an Android malware that was discovered misusing accessibility features in the device to steal user credentials from European banking applications has morphed into an altogether new botnet. Oscorp, a mobile malware built to attack several financial targets with the purpose of stealing funds from unsuspecting users, was revealed by Italy's CERT-AGID in late January. 

The Oscorp malware, like other Android malware, convinces users to provide them access to the Android Accessibility Service, which allows them to read text on the phone screen, determine an app installation prompt, traverse through the permission list, and install apps on the user's behalf. “Not being able to access the private files of other applications, the actions of these malicious apps are “limited” to the theft of credentials through phishing pages, to blocking the device and possibly to the capture of audio and video,” read the advisory published by Italy’s CERT-AGID. 

Malicious SMS messages were used to spread the malware, with attackers pretending as bank operators to deceive targets over the phone and secretly get access to the infected device using WebRTC protocol, allowing them to execute unlawful bank transfers. While no fresh activities have been detected since then, it appears as Oscorp has returned after a brief hiatus in the shape of the UBEL Android botnet. 

"By analysing some related samples, we found multiple indicators linking Oscorp and UBEL to the same malicious codebase, suggesting a fork of the same original project or just a rebrand by other affiliates, as its source-code appears to be shared between multiple [threat actors]," Italian cybersecurity company Cleafy said on Tuesday, charting the malware's evolution. 

UBEL, like its predecessor, is marketed on underground forums for $980 and asks for invasive permissions that allow it to read and send SMS messages, record audio, install and delete apps, initiate itself automatically after system boot, and exploit Android accessibility services to collect confidential data such as login credentials and two-factor authentication codes, the results of which are exfiltrated back to a remote server. 

Once installed on the system, the malware tries to disguise itself as a service and hide its presence from the target, allowing for long-term persistence. Surprisingly, using WebRTC to communicate with the hijacked Android phone in real-time eliminates the requirement to enroll a new device and take over an account in order to commit fraud. 

"The main goal for this [threat actor] by using this feature, is to avoid a 'new device enrolment', thus drastically reducing the possibility of being flagged 'as suspicious' since device's fingerprinting indicators are well-known from the bank's perspective," the researchers said.