This Thanksgiving, deals on your private data too

In a matter of years, we’ve seen Black Friday and Cyber Monday become two of the most anticipated days of the calendar year. While consumers eagerly await the chance to buy this season’s hottest gifts, what they don’t realize is that hackers are also anticipating a holiday treat: their personal data. This weekend, Zscaler uncovered a campaign where malware turning the holiday shopping season into an opportunity to scam large number of people by creating fake apps offering early access to Amazon.com Black Friday and Cyber Monday offers and deals.

The Zscaler research team recently came across one such fake amazon app which was masked as an Amazon.com Black Friday deals app, but actually intended to collect victim's personal data. The URL from where this fake app is downloaded is as shown below:

• URL :  http[:]//amazon[.]de[.]offer47263[.]cc/amazon[.]apk

From the URL it can be observed that the malware authors are using cyber squatting to fool the victim and portraying itself as a legitimate Amazon site.

Once the application gets installed it disguises itself as a legit Amazon app.

Icon

When the user starts this installed fake Amazon app, it loads another app named "com.android.engine" as seen below.

Loading application dynamically

This newly loaded child application asks for administrative privileges and other risky permissions like sending SMS and dialing phone numbers.

Permissions

This newly loaded app will first register itself as a service. Even if we remove the fake Amazon app, the "com.android.engine" app will stay persistent and keep doing its activity in the background. Once this malicious app is installed on the victim's phone, the fake Amazon application will start giving the error message: "Device not supported with App". This forces the victim to delete the fake amazon app thinking that there were some errors while installing it. As the malicious child app does not have any icon, it is quite difficult for the common users to remove the app.

The presence of this app can be seen in Settings>Apps>Running Applications section of device as shown below. 

Silently working in backgroud

Administrative access

This loaded malicious application has code for harvesting user's personal data.

The following code routine present in the app is used to collect victim's browser history and bookmarks.

Browser data

It is also able to harvest the call logs, received inbox messages and segregate it into sender's numbers, SMS body, received incoming call number and contact name etc as shown below.

Call logs

Inbox messages

The malicious app also gathers victims contact details.

Contacts

This particular piece of malware was also found to be communicating with an IP address in Canada, "198[.]50[.]169[.]251" on port 4467 probably sending the harvest data through network socket.

Hard coded IP

The following packet capture shows the malware communication with its C&C(Command and Control Center).

Packet Capture

Data being sent

Especially during this holiday season, consumers need to be aware of the applications they’re downloading and stay away from such fake apps. Always install applications from legitimate app stores and websites. Be aware of the permissions asked by the application during installation. Shopping apps should not be asking for access to your contacts or SMS. Keeping an eye on the permissions used by the app can save you from installing such fake apps.

Happy Thanksgiving to all !!

Infostealer APK Posing as Microsoft Word Document

Recently, we came across a piece of Android malware which was neither a porn app nor a battery status app, but was instead designed to look like a Microsoft Word document. This malicious app portrays itself as a document with an icon resembling Microsoft Word.

Due to the ubiquitous nature of mobile devices, its no wonder that PC based malware techniques are appearing in mobile domains. In early Windows malware attacks, attackers would often name the malicious files with eye-catching titles and use common icons to entice victims to open the file. We're seeing this same practice used for Android based malware.

Overview:
The malware portrays itself as a data file with an icon similar to that used by Microsoft Word documents and is entitled '资料' (Data). It runs with Administrative access and hence cannot be easily uninstalled. Once installed, the malware scans the device for SMS messages and other personally identifiable information such as the IMEI number, SIM card number, Device ID, victim's contact information,  etc. and sends this to the attacker via email.

Malicious APK posing as Microsoft Word File

Technical Details:
Once the malware is installed, it appears on the Android home screen as shown below:

Microsoft Word Icon

Initiation:
As soon as victim tries to start the app, it shows an explicit error stating "Installation errors, this software is not compatible with the phone" and the icon then disappears from the device screen.

Fake Error Message

When this error is being displayed, the app executes a few major functions as noted below:

• Sends SMS messages to a hard-coded number.
• Starts an Android service, named MyService.
• Starts an asynchronous thread (SmsTask) which runs in background.
• Starts another thread named MailTask, which also operates in background.
• Calls phone numbers specified by Attacker.

Sends SMS

Initially malware tries to send the victim's device IMEI code in a message body to a hardcoded number.

Calling SendMsg function

Assets.getInstallFlag gets the IMEI (or ESN number in case of CDMA devices)

IMEI code fetching

And finally sends the message. 

Sending Message

MyService Service:
The main task performed by MyService is to collect all the SMS messages from inbox of the victim's device.  Once that is done, it stores all the messages in its local logs.

Service fetching inbox messages

SmsTask Thread:
Apart from logging SMS messages, MyService was not sending these messages anywhere. This functionality is exhibited in the SmsTask thread.

SmsTask will also read the SMS messages and exfiltrates them.

Fetching inbox messages

Once the messages are collected, the app then sends them to attacker via email.

Calling SendMail method

A username and password for an email id were found hard-coded in the malware.

SendMail functionality

MailTask Thread:
MailTask's main role is to collect contact information from the victim's device and send it to attacker via the same functionality explained in case of SmsTask.

SmsTask Thread

Sending Mail:
The app sets up an SMTP host on port 465 for sending email.

Sending Mail

localMimeMessage contains the necessary data to be sent to attacker via email. In the case of SmsTask as mentioned above, localMimeMessage's body contains an SMS message list and in the MailTask instance, it contains contact numbers from victim's device.

Calling Functionality:
The malware was also designed to call phone numbers provided by an attacker via SMS.
It has a broadcast receiver registered to trigger whenever a new SMS is delivered.
The malware reads the SMS received from the attacker and acts accordingly.

In one instance, malware was trying to fetch phone numbers received in SMS messages and then calling them, as shown in screenshot below:

Broadcast Receiver

We were able to confirm that the campaign was initiated on October 10, 2015 and almost 300+ users had fallen prey to this malware. The attacker was able to successfully retrieve message details and contact lists from the infected users.

The following screenshots shows the list of emails received by the attacker:

Inbox

Further, each email titled "Message list" consists of full SMS conversations from the victims phones and email with subject "Contact list" contains a list of all the phone numbers fetched from victims contact diaries.

Messages from victim's device

Contacts from victim's phone

There were 300+ such emails found in the C&C admin panel. Such malware creates a significant privacy & financial risk as it obtains contact information and private SMS messages.

Prevention:
It is recommended that users download apps only from official Android stores like the Google Play store. If you are infected with malware, you can follow the steps mentioned in our previous blog for removing the malicious app.