TROJ_PGPCODER.A

Malware type: Trojan

Aliases: Virus.Win32.Gpcode.b (Kaspersky), GPcoder (McAfee), Trojan.Gpcoder (Symantec), TR/Gpcoder.A.1 (Avira), Troj/Gpcode-B (Sophos),

In the wild: Yes

Destructive: No

Language: English

Platform: Windows 95, 98, NT, ME, 2000, XP, and Server 2003

Encrypted: No

Overall risk rating:

Reported infections:

Damage potential:

High

Distribution potential:

Low

Description: 

This memory-resident Trojan arrives via Internet or copied from disks. Upon execution, it encrypts all files on the system having the following extensions:

  • ASC
  • DB
  • DB1
  • DB2
  • DBF
  • DOC
  • HTM
  • HTML
  • JPG
  • PGP
  • RAR
  • RTF
  • TXT
  • XLS
  • ZIP

As a consequence, the files with the above-mentioned extensions become unreadable after infection.

In order to ensure that only one instance of itself is running in memory at a time, it creates the mutex encoder_v1.0.

It then drops the file ATTENTION!!!.TXT into each folder where the encrypted files are located. The dropped .TXT file contains the following strings:

Some files are coded.
To buy decoder mail: n781567@yahoo.com
with subject: PGPcoder 000000000032

This Trojan also modifies the registry to ensure its automatic execution every Windows system startup.

For additional information about this threat, see:

Description created: May. 21, 2005 11:23:03 AM GMT -0800


TECHNICAL DETAILS


File type: PE

Memory resident:  Yes

Size of malware: 56,832 Bytes (compressed); 118,784 Bytes (uncompressed)

Initial samples received on: May 21, 2005

Compression type: UPX

Details:

Arrival and Installation

This memory-resident Trojan arrives via Internet or may be copied from optical media. Upon execution, it encrypts all files on the system having the following extensions:

  • ASC
  • DB
  • DB1
  • DB2
  • DBF
  • DOC
  • HTM
  • HTML
  • JPG
  • PGP
  • RAR
  • RTF
  • TXT
  • XLS
  • ZIP

As a consequence, the files with the above-mentioned extensions become unreadable after infection.

When this Trojan encounters a file that is in use and/or not writable, this means it cannot encode the said file. So, this Trojan copies the used file using the file name coder{original file name}.{original extension} in the same folder. It then encodes the copied file.

It creates the mutex encoder_v1.0 to ensure that only one instance of itself is running in memory at a time.

It then drops the file ATTENTION!!!.TXT into each folder where the encrypted files are located. The dropped .TXT file contains the following strings:

Some files are coded.
To buy decoder mail: n781567@yahoo.com
with subject: PGPcoder 000000000032

Autostart Techniques

This Trojan also modifies the registry to ensure its automatic execution every Windows system startup. It attempts to add the following entry:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
services = "{Complete path and file name}"

However, if the path or file name contains space, the data entry that will be set contains all the characters before the first occurrence of the space. Thus, this registry entry fails to point to the Trojan file.

Other Registry Modifications

This Trojan also creates the following registry entry which it uses to track its progress:

HKEY_CURRENT_USER\Software\Microsoft\Sysinf
cur_not_done = "{DWORD value}"

This entry contains the number of files that the Trojan has procesed. It changes dynamically as long as the Trojan is running in memory.

Other Details

This Trojan encodes files on any mounted drive and writable network share.

It also creates the file AUTOSAVE.IN in the Windows temporary folder. This file contains the list of files and folders found in the hard drives.

After performing its encryption routine, it creates the batch file TMP.BAT in the root folder. Afterward, it executes the said file. This batch file deletes the copy of the Trojan.

Analysis By: Jonathan N. San Jose

Updated By: Roy Dexter Dollentas Jimenez

Revision History:

First pattern file version: 2.638.13
First pattern file release date: May 21, 2005

SOLUTION


Minimum scan engine version needed: 6.810

Pattern file needed: 2.638.13

Pattern release date: May 21, 2005


Important note: The "Minimum scan engine" refers to the earliest Trend Micro scan engine version guaranteed to detect this threat. However, Trend Micro strongly recommends that you update to the latest version in order to get comprehensive protection. Download the latest scan engine here.

Solution:

AUTOMATIC REMOVAL INSTRUCTIONS

MANUAL REMOVAL INSTRUCTIONS

Identifying the Malware Program

To remove this malware, first identify the malware program.

  1. Scan your system with your Trend Micro antivirus product.
  2. NOTE all files detected as TROJ_PGPCODER.A.

Trend Micro customers need to download the latest pattern file before scanning their system. Other users can use Housecall, Trend Micro's online virus scanner.

Terminating the Malware Program

This procedure terminates the running malware process. You will need the name(s) of the file(s) detected earlier.

  1. Open Windows Task Manager.
    � On Windows 95, 98, and ME, press
    CTRL%20ALT%20DELETE
    � On Windows NT, 2000, XP, and Server 2003, press
    CTRL%20SHIFT%20ESC, then click the Processes tab.
  2. In the list of running programs*, locate the malware file(s) detected earlier.
  3. Select one of the detected files, then press either the End Task or the End Process button, depending on the version of Windows on your system.
  4. Do the same for all detected malware files in the list of running processes.
  5. To check if the malware process has been terminated, close Task Manager, and then open it again.
  6. Close Task Manager.

*NOTE: On systems running Windows 95, 98, and ME, Windows Task Manager may not show certain processes. You can use a third party process viewer such as Process Explorer to terminate the malware process. Otherwise, continue with the next procedure, noting additional instructions. If you were not able to terminate the malware process as described in the previous procedure, restart your system.

Editing the Registry

This malware modifies the system's registry. Users affected by this malware may need to modify or delete specific registry keys or entries. For detailed information regarding registry editing, please refer to the following articles from Microsoft:

  1. About the Registry and How to Use Registry Editor
  2. HOW TO: Backup, Edit, and Restore the Registry in Windows 95, Windows 98, and Windows ME
  3. HOW TO: Backup, Edit, and Restore the Registry in Windows NT 4.0
  4. HOW TO: Back Up, Edit, and Restore the Registry in Windows XP
  5. HOW TO: Backup, Edit, and Restore the Registry in Windows 2000

Removing Autostart Entries from the Registry

Removing autostart entries from the registry prevents the malware from executing at startup. In this procedure, you will need the name(s) of the file(s) detected earlier.

If the registry entries below are not found, the malware may not have executed as of detection. If so, proceed to the succeeding solution set.

  1. Open Registry Editor. Click Start>Run, type REGEDIT, then press Enter.
  2. In the left panel, double-click the following:
    HKEY_CURRENT_USER>Software>Microsoft>
    Windows>CurrentVersion>Run
  3. In the right panel, locate and delete the entry or entries whose data value is the malware path and file name of the file(s) detected earlier.

Removing Other Malware Entries from the Registry

  1. Still in the left panel, double-click the following:
    HKEY_CURRENT_USER>Software>Sysinf
  2. In the right panel, locate and delete the following entry:
    cur_not_done = "{DWORD Value}"
  3. Close Registry Editor.

Deleting Malware File

  1. Right-click Start then click Search� or Find�, depending on the version of Windows you are running.
  2. In the Named input box, type:
    ATTENTION!!!.TXT
  3. In the Look In drop-down list, select Local Disk C:, then press Enter.
  4. Once located, select all files by pressing Ctrl %20 A then press Delete.
  5. Repeat the previous steps for all other fixed and network drives attached to the machine.

Additional Windows ME/XP Cleaning Instructions

Users running Windows ME and XP must disable System Restore to allow full scanning of infected systems.

Users running other Windows versions can proceed with the succeeding procedure set(s).

Running Trend Micro Antivirus

Scan your system with Trend Micro antivirus and delete files detected as TROJ_PGPCODER.A. To do this, Trend Micro customers must download the latest pattern file and scan their system. Other Internet users can use HouseCall, Trend Micro's online virus scanner.




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