AGENT SMITH, the name of the software that takes advantage of Multiple Android vulnerabilities, such as the Janus flaw and the Man-in-the-Disk flaw, then the app injects malicious code into the Android Package (APK) file of targeted apps installed on a device and then automatically reinstall or updates them without the user’s knowledge or interaction.

“It’s not enough for this malware family to swap just one innocent application with an infected double. It does so for each and every app on the device as long as the package names are on its prey list,” the researchers wrote in their report published Wednesday”.

“Over time, this campaign will also infect the same device, repeatedly, with the latest malicious patches. This leads us to estimate there to be over 2.8 billion infections in total, on around 25 Million unique devices, meaning that on average, each victim would have suffered roughly 112 swaps of innocent applications.”


These details were captured by the Researchers from cybersecurity vendor Check Point have discovered a new kind of mobile malware targeting Android devices.

Based on their research, Agent Smith has been found to use its broad access privileges to display ads and profit off them.

Primarily targeting devices in India, and other Asian countries like Pakistan and Bangladesh, the malware has affected around 25 million unique devices, with each victim suffering “roughly 112 swaps of innocent applications.”

The infections were mainly reported on devices running Android 5 and 6, with most infections lasting for a period of at least two months.

In its present form, Agent Smith is being exploited for financial gain by serving malicious advertisements.

 But given its capabilities to impersonate popular Android apps, the researchers caution that:

 “There are endless possibilities for this sort of malware to harm a user’s device.”


According to the researchers, Agent Smith has been around since January 2016.

 Hackers began to use 9Apps as a distribution channel for adware by building a segment of dropper application.

9Apps is a third-party Android app store backed by UCWeb, which Alibaba Group acquired in 2014. One of its most popular products is the UC Browser — a web browser app with a strong presence in markets like China, India, and Indonesia.

The malware campaign, which began as a series of garden-variety adware blasts, intensified during the later half of 2018, before dropping significantly earlier this year.

In the recent months, the researchers also uncovered 11 infected apps on the Google Play Store that contained malicious yet dormant components used in Agent Smith, suggesting the threat actor is beginning to use Google’s own app distribution platform to spread adware. Google has since taken down the apps after Check Point reported their findings.

Armed with this information, the researchers connected the Agent Smith campaign to a Chinese internet company located in Guangzhou. The tech firm, they discovered, operated an actual front-end business to help Chinese Android developers publish and promote their apps on overseas platforms.

But according to Check Point, it found ads for job roles that related to the Agent Smith malware infrastructure and had no connection to the company’s real business.

They also revealed that the “Agent Smith prey list does not only have popular yet Janus vulnerable apps to ensure high proliferation, but also contain competitor apps of actor’s legitimate business arm to suppress competition.”


  •  Loader Module.
  •  Core Module.
  •  Boot Module.
  •  Patch Module.
  • AdSDK Module.

The initial application distributing the malware contains a module called Loader. The only purpose of this module is to decrypt, extract, and run the second stage module named Core.


Once executed, the Core module communicates with the attackers’ command-and-control (C&C) server to receive a list of popular apps that needs to be targeted.

Using Janus Vulnerability:

If it finds a match installed on the victim’s device, the core module tries to infect the targeted APK using the Janus vulnerability or by simply recompiling the APK with a malicious payload.

Using Man-In-The-Disk Attack:

Further, to automatically install the modified APK and replace its original version without users’ consent, attackers utilize a series of 1-day vulnerabilities, including man-in-the-disk attack.


This module is included in the malicious payload that was bundled with the original app and worked the same as the Loader module. It extracts and executes a malicious payload, called the Patch module when a victim runs the modified application.


The patch module has been designed to prevent modified applications from getting legitimate updates, which if installed, would revert all malicious changes.

“While investing a lot of resources in the development of this malware, the actor behind Agent Smith does not want a real update to remove all of the changes made, so here is where the Patch module comes in to play”

“With the sole purpose of disabling automatic updates for the infected application, this module observes the update directory for the original application and removes the file once it appears.”


This is the actual payload that displays ads to the victims for financial gain and further also infects the device with other adware families.

However, the researchers warn that this modular malware could be easily adapted for far more intrusive and harmful purposes, such as stealing sensitive information—from private messages to banking credentials and much more.


“AGENT SMITH has some Greedy Tactics”.

 Check Point noted:

 “It’s not enough for this malware family to swap just one innocent application with an infected double. It does so for each and every app on the device as long as the package names are on its prey list.”

The application words on 9Apps with hundreds of dropper apps — mostly variants of photo utility, games, or adult entertainment related apps.

Agent Smith specifically targeted users from India, but researchers also found successful penetration in Saudi Arabia, the UK, and the US. India alone accounts for over 15 million infected Android devices.

In addition, the research found that the top 5 most infectious droppers alone have been downloaded more than 7.8 million times, with Samsung and Xiaomi devices accounting for the most infections in India.


Since Agent Smith has mostly infected users who downloaded apps from third-party app stores, users are highly recommended always to download apps from trusted app stores to mitigate the risk of infection. Also, download apps only from trusted developers.

Users are also advised to uninstall any apps they suspect may be malicious by heading on to Settings Menu, clicking Apps or Application Manager, and then Scroll to the suspected app and uninstall it.

Since the key vulnerability Agent Smith is exploiting dates back to 2017 and has already been patched, mobile app developers are recommended to implement the latest APK Signature Scheme V2 to prevent malicious apps from leveraging Android’s Janus vulnerability against their apps.

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