arrow_back
search
close

TROJ_AGENT.AATB

October 13, 2012
 ALIASES:

TrojanDownloader:Win32/Small.gen!I (Microsoft); Generic.dx (McAfee); W32.SillyFDC (Symantec); Worm.Win32.AutoRun.afn (Kaspersky); Trojan.Win32.Generic!BT (Sunbelt); Dropped:Trojan.Dropper.Rootkit.NAX (FSecure)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It modifies files, disabling programs and applications from properly running.

  TECHNICAL DETAILS

File Size:

57,157 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

24 May 2012

Arrival Details

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Installation

This Trojan drops the following copies of itself into the affected system:

  • %Windows%\Downloaded Program Files\appmgmd.exe

(Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)

Other System Modifications

This Trojan modifies the following files:

  • %System%\appmgmts.dll

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

It deletes the following files:

  • %Windows%\SoftwareDistribution\DataStore\Logs\edbtmp.log

(Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)

It adds the following registry keys:

HKEY_CLASSES_ROOT\CLSID\{8F61586C-5D1B-4c76-BB3A-3B88F96A18B0}

HKEY_CLASSES_ROOT\CLSID\{8F61586C-5D1B-4c76-BB3A-3B88F96A18B0}\
InprocServer32

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\ShellServiceObjectDelayLoad
adsnv = "{8F61586C-5D1B-4c76-BB3A-3B88F96A18B0}"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{8F61586C-5D1B-4c76-BB3A-3B88F96A18B0}\InprocServer32
ThreadingModel = "Both"

It modifies the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\Session Manager\SFC
ProgramFilesDir = "%Program Files%"

(Note: The default value data of the said registry entry is %Program Files%.)

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\Session Manager\SFC
CommonFilesDir = "%Program Files%\Common Files"

(Note: The default value data of the said registry entry is %Program Files%\Common Files.)

Dropping Routine

This Trojan drops the following files:

  • %System Root%\sysret.dat
  • %System%\adsnv.dll
  • %System Root%\ntload
  • %System Root%\sysret.sys
  • %System Root%\ks.bat
  • %System%\dllcache\appmgmts.dll

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.. %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://www.{BLOCKED}updates.net/asphack/log.asp?{random characters}
  • http://www.{BLOCKED}updates.net/zjgmir.exe

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.200

Step 1

For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

Step 2

Delete this registry key

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_CLASSES_ROOT\CLSID
    • {8F61586C-5D1B-4c76-BB3A-3B88F96A18B0}
  • In HKEY_CLASSES_ROOT\CLSID\{8F61586C-5D1B-4c76-BB3A-3B88F96A18B0}
    • InprocServer32

Step 3

Delete this registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\ShellServiceObjectDelayLoad
    • adsnv = "{8F61586C-5D1B-4c76-BB3A-3B88F96A18B0}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{8F61586C-5D1B-4c76-BB3A-3B88F96A18B0}\InprocServer32
    • ThreadingModel = "Both"

Step 4

Restore this modified registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\Session Manager\SFC
    • From: ProgramFilesDir = "%Program Files%"
      To: ProgramFilesDir = ""%Program Files%""
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\Session Manager\SFC
    • From: CommonFilesDir = "%Program Files%\Common Files"
      To: CommonFilesDir = ""%Program Files%\Common Files""

Step 5

Search and delete these files

[ Learn More ]
There may be some component files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.
  • %System Root%\sysret.dat
  • %System%\adsnv.dll
  • %System Root%\ntload
  • %System Root%\sysret.sys
  • %System Root%\ks.bat
  • %System%\dllcache\appmgmts.dll

Step 6

Scan your computer with your Trend Micro product to delete files detected as TROJ_AGENT.AATB. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.

Step 7

Restore deleted/modified files and/or registry entries from backup

*Note: Only Microsoft-related files/keys/values will be restored. If this malware/grayware also deleted registry keys/values related to programs that are not from Microsoft, please reinstall those programs on your computer.

    • %System%\appmgmts.dll

Step 8

Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.

  • %Windows%\SoftwareDistribution\DataStore\Logs\edbtmp.log


Did this description help? Tell us how we did.