Nikolaos Chrysaidos

Nikolaos Chrysaidos

21 November 2016

3 million Android phones vulnerable due to pre-installed rootkit

A backdoor has been discovered that could allow attackers to take complete control of certain Android devices.

Read More

Mobile Security

Nikolaos Chrysaidos

18 November 2016

Your Android could be sending messages to China

A pre-installed backdoor on more than 700 Android devices transmits data to a server in China every 72 hours.

Read More

Mobile Security

Nikolaos Chrysaidos

31 October 2016

Android Trojan GM Bot is evolving and targeting more than 50 banks worldwide

GM Bot has targeted hundreds of thousands of mobile users in the last quarter.

Read More

Mobile Security

Nikolaos Chrysaidos

31 March 2016

Metaphor exploit: A follow-up to Stagefright that puts millions of Android devices at risk

Android-StageFright-Exploit

(Image via Enterprise Security Today)

Last summer, it was nearly impossible to avoid the news about the Stagefright vulnerability. At the time of its unveiling, security researchers believed Stagefright to be the worst Android vulnerability to be discovered. Nearly a year after its discovery, Metaphor is the most recent embodiment of the vulnerability to rear its ugly head.

Social engineering, a popular technique used to lure victims into becoming infected with malware, plays a key role in encouraging victims to open web pages that allow the exploit to take place and for Metaphor to be fully effective.

Read More

Mobile Security

Nikolaos Chrysaidos

5 November 2015

DroidJack isn’t the only spying software out there: Avast discovers that OmniRat is currently being used and spread by criminals to gain full remote control of devices.

There’s more than one RAT

On Friday, I discovered OmniRat, a program similar to DroidJack. DroidJack is a program that facilitates remote spying and recently made news when European law enforcement agencies made arrests and raided the homes of suspects as part of an international malware investigation.

OmniRat and DroidJack are RATs (remote administration tools) that allow you to gain remote administrative control of any Android device. OmniRat can also give you remote control of any Windows, Linux or Mac device. Remote administrative control means that once the software is installed on the target device, you have full remote control of the device.

On their website, OmniRat lists all of the things you can do once you have control of an Android, which include: retrieving detailed information about services and processes running on the device, viewing and deleting browsing history, making calls or sending SMS to any number, recording audio, executing commands on the device and more.

OmniRat

Read More

Mobile Security, Threat Research, Security News

Nikolaos Chrysaidos

24 July 2015

Malware that Just Won’t Give Up on Google Play

A team of malware authors is playing a cat and mouse game with Google. The game goes like this: they upload their malware, Google Play quickly takes it down, they upload a new mutation and Google takes it down. Current status of the game: the malware is back on Google Play. So far, the malicious apps have infected hundreds of thousands of innocent victims.

In April, we discovered porn clicker malware on Google Play posing as the popular Dubsmash app.

Mutant malware

Two days ago, we reported that a mutation of the porn clicker malware, created by a Turkish group of malware authors, made its way back onto Google Play, but have since been removed from the Play Store.

Once the apps were downloaded they did not do anything significant when opened by the user, they just showed a static image. However, once the unsuspecting victim opened his/her browser or other apps, the app began to run in the background and redirect the user to porn sites. Users may not have necessarily understood where these porn redirects were coming from, since it was only possible to stop them from happening once the app was killed. Fellow security researchers at Eset reported that more apps with this mutation were on Google Play earlier this week. Eset also reported that the original form of the malware was uploaded to Google Play multiple times in May. Our findings combined with that from Eset, prove that these malware authors are extremely persistent and determined to make Google Play a permanent residency for their malware.

I’ll be back…

Read More

Mobile Security, Threat Research, Security News

Nikolaos Chrysaidos

10 February 2015

Mobile Crypto-Ransomware Simplocker now on Steroids

In June 2014, we told you about mobile ransomware called Simplocker that actually encrypted files (before Simplocker, mobile ransomware only claimed to encrypt files to scare users into paying). Simplocker infected more than 20,000 unique users, locking Android devices and encrypting files located in the external storage. Then, it asked victims to pay a ransom in order to “free” the hijacked device. It was easy to decrypt the files affected by this variant of Simplocker, because the decryption key was hardcoded inside the malware and was not unique for each affected device.

Dangerous unique keys

keyBut now there is a new, more sophisticated variant of Simplocker in town that has already infected more than 5,000 unique users within days of being discovered. The reason why this variant is more dangerous than its predecessor is that it generates unique keys for each infected device, making it harder to decrypt infected devices.

To use an analogy, the original variant of Simplocker used a “master key” to lock devices, which made it possible for us to provide a “copy of the master key” (in the form of an app, Avast Ransomware Removal) to unlock already infected devices. The new variant however, locks each device with a “different key” which makes it impossible to provide a solution that can unlock each infected device, because that would require us to “make copies” of all the different “keys”.

Why would anybody install Simplocker?!

The reason why people install this new variant of Simplocker is because it goes undercover, meaning people don’t even realize that what they are installing is ransomware!

Fake Flash Tricky Simplocker pretends to be a real app.

 

In this case, the new variant of Simplocker uses the alias “Flash Player” and hides in malicious ads that are hosted on shady sites. These ads mostly “alert” users that they need Flash Player installed in order to watch videos. When the ad is clicked on, the malicious app gets downloaded, notifying the user to install the alleged Flash Player app. Android, by default, blocks apps from unofficial markets from being installed, which is why users are notified that the install is being blocked for security reasons.
Device Admin Request

 

Users should listen to Android’s advice. However, users can go into their settings to deactivate the block and download apps from unknown sources. Once installed, a “Flash Player” app icon appears on the device and when it is opened the “Flash Player” requests the user grant it administrator rights, which is when the trouble really begins.

As soon as the app is granted administrator rights, the malware uses social engineering to deceive the user into paying ransom to unlock the device and decrypt the files it encrypted. The app claims to be the FBI, warning the user that they have found suspicious files, violating copyright laws demanding the user pay a $200 fine to decrypt their files.

device-2015-02-05-143216 FBI warning is an example of social engineering

What should I do if I have been infected?

We do NOT recommend you pay the ransom. Giving into these tactics makes malware authors believe they are succeeding and encourages them to continue.

If you have been infected by this new strain of Simplocker, back up the encrypted files by connecting your smartphone to your computer. This will not harm your computer, but you may have to wait until a solution to decrypt these files has been found. Then boot your phone into safe mode, go into the administrator settings and remove the malicious app and uninstall the app from the application manager.

Avast protects users against Simplocker

Avast Mobile Security protects users against both the old and new variant of Simplocker, the new variant is detected as: Android:Simplocker-AA.

A more technical look under the hood:

As the fake FBI warning is being shown to users, the malware continues working in the background, doing the following:

Read More

Mobile Security, Threat Research, Security News

Nikolaos Chrysaidos

3 December 2014

Is backing up your data the same as exposing it? In this case - Yes!

Losing contacts from your mobile phone is highly inconvenient. There's seems to be a solution - You can find them online! The catch? Your contacts are in a publicly accessible place.

Read More

Tips, Mobile Security, Threat Research, Security News

Nikolaos Chrysaidos

7 May 2014

Fake government ransomware holding Android devices hostage

Ransomware, which has already made its rounds on Windows, is now increasingly targeting the Android operating system. A new piece of mobile malware claiming to be the government under the name Android: Koler-A is now targeting users.

Read More

Mobile Security, Threat Research, Security News

Nikolaos Chrysaidos

31 March 2014

The Gray-zone of malware detection in Android OS

Does the title of this blog post have a mysterious meaning? Not exactly.

In this first part about the gray-zone of Android malware detections, I will introduce the Android:SecApk, a detection regarding the protection that the App Shield (Bangcle) offers to Android applications (.apk). This detection has a big sample set that is still growing. Some SecApk wrapped samples that existed or still exist in the Google Play Store and third party stores, can be seen in the table below.

MD5

Name \ Info

F1EF5B8C671B2146C2A2454ECF775E47

G锁屏冰雪奇缘之来自星星的你V1.0.apk

\ PUP – An application to promote a specific movie. Potentially unwanted because of the extended permissions that was requested.

Current Status: Removed from Google Play

10bd28d4f56aff83cb6d31b6db8fdbd2

Cut_the_bird.apk

\PUP – A game that have potentially unwanted permissions that they can drive to loss of private personal info.

05ffb6f34e40bb1cf8f9628e5647d5e3

aini1314langmanzhutisuoping_V2.5_mumayi_700e0.apk

\PUP – A screensaver application that has permissions unrelated with the purpose of the app.

d6b40bbb79b54c09352a2e0824c0adba

3D职业乒乓球.apk

\Pup – This application is a tennis game. Potentially unwanted because of the extended permissions that was requested.

eefd2101e6a0b016e5a1e9859e9c443e

eefd2101e6a0b016e5a1e9859e9c443e.apk

\Malware – This app steal personal data and SMS messages from the user.

 

The App Shield is an online service that, after a submission of an .apk, encrypts it and adds some layers of protection. The procedure of the encryption and protection of the apk will be discussed with more detail during the course of the second part of this blog post.

Starting with the submission process, a clean app named AvstTest.apk uploaded to the service. The exported .apk was renamed as AvstTest[SecApk].apk. In addition, apktool and dex2jar used accordingly to decode the .apk resources and convert the ‘.dex’ files to ‘.jar’.

Folder structure

Read More

Tips, Mobile Security, Threat Research, Security News