Threat Explorer

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Trojan.Celptex

Trojan.Celptex

Discovered:
July 09, 2014
Updated:
July 11, 2014
Infection Length:
112, 640 Bytes
Systems Affected:
Windows
Trojan.Celptex is a Trojan horse that performs malicious activities on the compromised computer.

Antivirus Protection Dates

  • Initial Rapid Release version July 09, 2014 revision 018
  • Latest Rapid Release version January 25, 2017 revision 025
  • Initial Daily Certified version July 09, 2014 revision 019
  • Latest Daily Certified version January 26, 2017 revision 001
  • Initial Weekly Certified release date July 16, 2014
Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.
Once executed, the Trojan creates the following files:
  • %Temp%\libcurl-4.dll
  • %Temp%\pthreadGC2.dll
  • %Temp%\zlib1.dll

It then creates the following alternate data streams (ADS):
  • %Temp%:rnd.dat
  • %Temp%:[RANDOM CHARACTERS].dat
  • %Temp%:pid1
  • %Temp%:pid2

The Trojan creates the following registry entries so that it runs whenever Windows starts:
  • %HKEY_LOCAL_MACHINE%\SOFTWARE\microsoft\windows\currentversion\run\"svchost:regsvr32 /s" = "%Temp%:[RANDOM CHARACTERS].dat"
  • %HKEY_LOCAL_MACHINE%\SOFTWARE\microsoft\windows\currentversion\run\"[LETTER A REPEATED]" = "1"

The Trojan then launches a new explorer.exe process and infects it with malicious code.

The infected explorer.exe process may then perform the following actions:
  • Carries out the following checks to make sure it is not running in a sandbox or on a virtual machine:
  • Checks for running debuggers
  • Checks for a number of keywords in the environment: SANDBOX, VIRUS, MALWARE, ANUBIS, MALWR
  • Checks for the presence of sbiedll.dll (used by some sandbox software)
  • Checks for the presence of procedures that would suggest the sample is running under Linux
  • Checks for the presence of registry keys related to VirtualBox/Vmware/Qemu emulation software

The infected explorer.exe then creates the following mutexes:
  • [COMPUTER SPECIFIC VALUE]Pe
  • [COMPUTER SPECIFIC VALUE]le
  • [COMPUTER SPECIFIC VALUE]ltc

It also connects to the following remote location in order to check Internet connectivity:
http://www.google.com/search?q=google

The Trojan then gathers the following information from the compromised computer:
  • Windows version
  • Hostname

It then sends the gathered information to the following remote location:
[http://]207.12.89.163/inde[REMOVED]?product_id=[COMPUTER SPECIFIC VALUE]-FbsGEN&dispatch=[HOSTNAME]&target=[WINDOWS VERSION]&v=1&q=009

The Trojan will attempt to infect the explorer.exe process multiple times, causing multiple explorer.exe processes to be created on the compromised computer.

The Trojan will then attempt to inject the cpuminer application into explorer.exe in order to use the compromised computer for cryptocurrency mining.

Recommendations

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 computer has been affected by this risk.

Before proceeding further we recommend that you run a full system scan . If that does not resolve the problem you can try one of the options available below.



FOR NORTON USERS
If you are a Norton product user, we recommend you try the following resources to remove this risk.


Removal Tool

If you have an infected Windows system file, you may need to replace it using the Windows installation CD .


How to reduce the risk of infection
The following resources provide further information and best practices to help reduce the risk of infection.


FOR BUSINESS USERS
If you are a Symantec business product user, we recommend you try the following resources to remove this risk.


Identifying and submitting suspect files
Submitting suspicious files to Symantec allows us to ensure that our protection capabilities keep up with the ever-changing threat landscape. Submitted files are analyzed by Symantec Security Response and, where necessary, updated definitions are immediately distributed through LiveUpdate™ to all Symantec end points. This ensures that other computers nearby are protected from attack. The following resources may help in identifying suspicious files for submission to Symantec.


Removal Tool

If you have an infected Windows system file, you may need to replace it using the Windows installation CD .


How to reduce the risk of infection
The following resource provides further information and best practices to help reduce the risk of infection.
Protecting your business network



MANUAL REMOVAL
The following instructions pertain to all current Symantec antivirus products.


1. Performing a full system scan
How to run a full system scan using your Symantec product


2. Restoring settings in the registry
Many risks make modifications to the registry, which could impact the functionality or performance of the compromised computer. While many of these modifications can be restored through various Windows components, it may be necessary to edit the registry. See in the Technical Details of this writeup for information about which registry keys were created or modified. Delete registry subkeys and entries created by the risk and return all modified registry entries to their previous values.
Writeup By: Cathal Mullaney