Threat Explorer

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22 February 2011
23 February 2011
Systems Affected:
Android.Pjapps is a Trojan horse that has been embedded on third party applications and opens a back door on the compromised device. It retrieves commands from a remote command and control server.

Antivirus Protection Dates

  • Initial Rapid Release version 22 February 2011 revision 022
  • Latest Rapid Release version 01 September 2019 revision 019
  • Initial Daily Certified version 22 February 2011 revision 021
  • Latest Daily Certified version 13 August 2019 revision 008
  • Initial Weekly Certified release date 23 February 2011
Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.
The Trojan is typically bundled with an application available on unregulated third-party Android marketplaces.

When the Trojan is executed, it requests permissions to perform the following actions:
  • Open network sockets
  • Send and monitor incoming SMS messages
  • Read and write to the user's browsing history and bookmarks
  • Install packages
  • Write to external storage
  • Read the phone's state (i.e. out of service, radio off, etc)

It then creates a service that runs in the background. The threat launcher is triggered whenever the reception signal of the device changes.

When the service is started it tries to register itself using the following URL:[PARAMETERS]

Note: [PARAMETERS] is a variable that contains the following information from the device
  • IMEI
  • DeviceID
  • Line Number
  • Subscriber ID
  • SIM serial number

The threat may send a message to a mobile number controlled by the attackers with the infected device's IMEI number. The mobile number where this message is sent to is obtained from the following URL:[PARAMETERS]

The threat downloads commands from the following location:

The commands are enclosed within an .xml file, and include the following commands:
  • note
    This command is most probably meant to be used to send text messages to premium-rate numbers. A mobile number and content have to be specified, and two additional actions can be performed:

    • blacklisting—If specified, the mobile’s number will be sent to a remote server to check whether it has been blacklisted, in which case the message won’t be sent. The URL of the service has to be sent as a parameter to the command and the blacklist check will be performed issuing a request with the following format:
      ($blacklist_url) + "/?tel=" + mobilenumber
    • response blocking—Android.Pjapps also listens for incoming messages, this allows the note command to specify rules to drop inbound messages if certain conditions are met, so the user doesn’t read them. Beginning and end-of-message strings are among the supported filters.

  • push
    This command performs SMS-spamming and requires the following parameters:

    • <smscontent>—Content of the text message
    • <smsurl>—A URL to add at the end of the message contents
    • <tel>—Mobile numbers to send the text to, separated by '#'

  • soft
    This command is used to install packages on to the compromised device. The packages are downloaded from a remote URL that has to be sent along with the command as a parameter.

  • window
    This command makes the mobile navigate to a given website. Android.Pjapps has a preference of which browser to use, checking for the presence of the following browsers:
  • mark
    The mark command is used to add bookmarks to the compromised device. When the service is first launched, Android.Pjapps may also, by default, add the following bookmarks to the device:

    • com.uc.browser
    • com.tencent.mtt
    • mobi.mgeek.TunnyBrowser
    • com.skyfire.browser
    • com.kolbysoft.steel

  • xbox
    This command has been found in Android.Pjapps parsing code but it seems to be unimplemented.


Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

  • Use a firewall to block all incoming connections from the Internet to services that should not be publicly available. By default, you should deny all incoming connections and only allow services you explicitly want to offer to the outside world.
  • Enforce a password policy. Complex passwords make it difficult to crack password files on compromised computers. This helps to prevent or limit damage when a computer is compromised.
  • Ensure that programs and users of the computer use the lowest level of privileges necessary to complete a task. When prompted for a root or UAC password, ensure that the program asking for administration-level access is a legitimate application.
  • Disable AutoPlay to prevent the automatic launching of executable files on network and removable drives, and disconnect the drives when not required. If write access is not required, enable read-only mode if the option is available.
  • Turn off file sharing if not needed. If file sharing is required, use ACLs and password protection to limit access. Disable anonymous access to shared folders. Grant access only to user accounts with strong passwords to folders that must be shared.
  • Turn off and remove unnecessary services. By default, many operating systems install auxiliary services that are not critical. These services are avenues of attack. If they are removed, threats have less avenues of attack.
  • If a threat exploits one or more network services, disable, or block access to, those services until a patch is applied.
  • Always keep your patch levels up-to-date, especially on computers that host public services and are accessible through the firewall, such as HTTP, FTP, mail, and DNS services.
  • Configure your email server to block or remove email that contains file attachments that are commonly used to spread threats, such as .vbs, .bat, .exe, .pif and .scr files.
  • Isolate compromised computers quickly to prevent threats from spreading further. Perform a forensic analysis and restore the computers using trusted media.
  • Train employees not to open attachments unless they are expecting them. Also, do not execute software that is downloaded from the Internet unless it has been scanned for viruses. Simply visiting a compromised Web site can cause infection if certain browser vulnerabilities are not patched.
  • If Bluetooth is not required for mobile devices, it should be turned off. If you require its use, ensure that the device's visibility is set to "Hidden" so that it cannot be scanned by other Bluetooth devices. If device pairing must be used, ensure that all devices are set to "Unauthorized", requiring authorization for each connection request. Do not accept applications that are unsigned or sent from unknown sources.
  • For further information on the terms used in this document, please refer to the Security Response glossary.
You may have arrived at this page either because you have been alerted by your Symantec product about this risk, or you are concerned that your device has been affected by this risk.

Install Norton Mobile Security
If you do not already have Norton Mobile Security installed on your device, please download the product from the Android marketplace .

Alternatively, you can navigate to the website from your device and download the product from there by completing the following steps:
  1. Select the 90-Day free download.
  2. Click on the Android icon to begin downloading the product.
  3. Click on Install in order to accept the permissions that are being requested by the program.
  4. Next, click Open and then Agree & Launch.

Note: The first time the product runs, you will be required to enter a code that is displayed on the screen in order to activate the product. Enter the provided code and press Submit .

Run a full system scan
Run a full system scan using Norton Mobile Security to remove this risk from the device. To do this, please perform the following actions:
  1. Navigate to the Anti-Malware tab.
  2. Click Scan Now.

Manual removal
To remove this risk manually, please perform the following actions:
  1. Open the Google Android Menu.
  2. Go to the Settings icon and select Applications.
  3. Next, click Manage.
  4. Select the application and click the Uninstall button.
Writeup By: Mario Ballano