Dark Reading is part of the Informa Tech Division of Informa PLC

This site is operated by a business or businesses owned by Informa PLC and all copyright resides with them.Informa PLC's registered office is 5 Howick Place, London SW1P 1WG. Registered in England and Wales. Number 8860726.

Application Security

3/10/2021
03:45 PM
Connect Directly
Twitter
LinkedIn
RSS
E-Mail
50%
50%

Malware Operator Employs New Trick to Upload Its Dropper into Google Play

Check Point researchers recently discovered the Clast82 dropper hidden in nine legitimate Android utility apps.

Researchers at Check Point recently discovered that the operator of a malware tool that breaks into mobile users' financial accounts was employing a novel new method to sneak its malware into Google's official Android Play mobile app store.

The method involved using Google's own Firebase platform for command-and-control (C2) communications and using GitHub as a third-party hosting platform for downloading the main malware. It allowed the attacker to fool and pass the security checks that Google conducts on all applications before they can be uploaded to its app store or downloaded on a device.

Related Content:

Malicious Android Apps Slip Through Google Play Protection

Special Report: How IT Security Organizations Are Attacking the Cybersecurity Problem

New From The Edge: How to Protect Vulnerable Seniors From Cybercrime

Check Point said its researchers in January discovered a new malware dropper hidden inside nine legitimate and known Android utility apps on Google Play store. The poisoned apps included several VPNs, a barcode reader, a music player, and a voice call recorder. "Those apps [were] based on open-source projects," says Aviran Hazum, Check Point's manager of mobile research. "The actor [could] just download the code, insert the malicious components, and compile the app."

When a user downloaded any of the weaponized apps — which Google has now removed from its Play store — the app would perform as expected even as it executed malicious activity in the background, Hazum said.

The researchers found that the dropper, called Clast82, was designed specifically to evade detection by Google's Play Protect scanning mechanisms during the app evaluation period. Once the evaluation was complete, the malware author essentially turned on the malicious behavior and got the dropper to install the AlienBot Banker and MRAT – two mobile malware families.

To achieve this, the malware operator used an account on Google's Firebase mobile app development platform as its C2 server. During Google's application evaluation period, the threat actor used the Firebase account to set a specific parameter in the dropper to a value such that its malicious capabilities were essentially switched off. Once Google had approved and published the app, the attacker enabled the parameter to trigger the malicious activity. "It just [didn't] drop any payload," during the evaluation process Hazum says. "Once the evaluation period ended, the actor [turned on] the malicious behavior."

Once enabled, the dropper downloaded AlienBot Banker from where it was stored in a GitHub account and changed the application's behavior completely. The threat actor created a new developer user-account and GitHub repository for each of the weaponized apps so they could distribute different payloads to devices that were infected by the apps.

Check Point described the second-stage AlienBot as malware-as-a-service for Android devices. The malware is designed to inject malicious code into banking and other financial applications to give attackers control of the account. Among its capabilities is a feature for bypassing two-factor authentication by intercepting and stealing SMS messages. MRAT, meanwhile, is malware that Clast82 downloads concurrently with AlienBot that allows a remote adversary to gain the same kind of control over a mobile device that a user actually holding the device would have.

Continuing Problem
Check Point's recent discovery is the latest reminder of how threat actors are continuing to find ways to upload malicious software to the official mobile app store of Google and, to a relatively lesser extent, Apple as well. Only last month researchers from Malwarebytes reported on how attackers had managed to insert malicious code in a new version of a very popular app on Play called Barcode Scanner. Millions of users are later believed to have installed the malicious version.

In recent years, both Google and Apple — the biggest players in the mobile space — have implemented numerous mechanisms for vetting applications before allowing them into their official app stores. In 2019, Google announced an alliance with ESET, Zimperium, and Lookout under which the three security vendors are working with Google to identify malicious and potentially harmful applications before they get published in the Play app store. Google's Play Protect, available by default on all Android devices since 2017, is a mechanism designed to help mobile users by scanning apps they download from Play for malware and other potentially harmful behavior.

"Google is invested in the fight against malware in their store," Hazum says. "But as can be shown by [the latest] campaign, it's not enough."

Jai Vijayan is a seasoned technology reporter with over 20 years of experience in IT trade journalism. He was most recently a Senior Editor at Computerworld, where he covered information security and data privacy issues for the publication. Over the course of his 20-year ... View Full Bio
 

Recommended Reading:

Comment  | 
Print  | 
More Insights
Comments
Newest First  |  Oldest First  |  Threaded View
Commentary
Cyberattacks Are Tailored to Employees ... Why Isn't Security Training?
Tim Sadler, CEO and co-founder of Tessian,  6/17/2021
Edge-DRsplash-10-edge-articles
7 Powerful Cybersecurity Skills the Energy Sector Needs Most
Pam Baker, Contributing Writer,  6/22/2021
News
Microsoft Disrupts Large-Scale BEC Campaign Across Web Services
Kelly Sheridan, Staff Editor, Dark Reading,  6/15/2021
Register for Dark Reading Newsletters
White Papers
Video
Cartoon
Current Issue
The State of Cybersecurity Incident Response
In this report learn how enterprises are building their incident response teams and processes, how they research potential compromises, how they respond to new breaches, and what tools and processes they use to remediate problems and improve their cyber defenses for the future.
Flash Poll
How Enterprises are Developing Secure Applications
How Enterprises are Developing Secure Applications
Recent breaches of third-party apps are driving many organizations to think harder about the security of their off-the-shelf software as they continue to move left in secure software development practices.
Twitter Feed
Dark Reading - Bug Report
Bug Report
Enterprise Vulnerabilities
From DHS/US-CERT's National Vulnerability Database
CVE-2021-2322
PUBLISHED: 2021-06-23
Vulnerability in OpenGrok (component: Web App). Versions that are affected are 1.6.7 and prior. Easily exploitable vulnerability allows low privileged attacker with network access via HTTPS to compromise OpenGrok. Successful attacks of this vulnerability can result in takeover of OpenGrok. CVSS 3.1 ...
CVE-2021-20019
PUBLISHED: 2021-06-23
A vulnerability in SonicOS where the HTTP server response leaks partial memory by sending a crafted HTTP request, this can potentially lead to an internal sensitive data disclosure vulnerability.
CVE-2021-21809
PUBLISHED: 2021-06-23
A command execution vulnerability exists in the default legacy spellchecker plugin in Moodle 3.10. A specially crafted series of HTTP requests can lead to command execution. An attacker must have administrator privileges to exploit this vulnerabilities.
CVE-2021-34067
PUBLISHED: 2021-06-23
Heap based buffer overflow in tsMuxer 2.6.16 allows attackers to cause a Denial of Service (DoS) by running the application with a crafted file.
CVE-2021-34068
PUBLISHED: 2021-06-23
Heap based buffer overflow in tsMuxer 2.6.16 allows attackers to cause a Denial of Service (DoS) by running the application with a crafted file.