BKDR_AGENTT.DQ
VirTool:Win32/DelfInject.gen!AU (Microsoft); W32/Hamweq.worm.h (McAfee); W32.Pilleuz!gen2, Packed.Generic.291 (Symantec); Trojan.Win32.Agent.covk (Kaspersky); Backdoor.Win32.EggDrop.bmg (v) (Sunbelt); Rogue:W32/FakeAv.BI (FSecure)
Windows 2000, Windows XP, Windows Server 2003
Threat Type: Backdoor
Destructiveness: No
Encrypted:
In the wild: Yes
OVERVIEW
This backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.
TECHNICAL DETAILS
Arrival Details
This backdoor 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 backdoor drops the following copies of itself into the affected system:
- %System Root%\RECYCLER\S-1-5-21-0636360875-2094037254-701732380-5722\mwau.exe
(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)
It creates the following folders:
- %System Root%\RECYCLER
- %System Root%\RECYCLER\S-1-5-21-0636360875-2094037254-701732380-5722
(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)
Autostart Technique
This backdoor adds the following registry entries to enable its automatic execution at every system startup:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Taskman = "%System Root%\RECYCLER\S-1-5-21-0636360875-2094037254-701732380-5722\mwau.exe"
Other System Modifications
This backdoor adds the following registry keys:
HKEY_CURRENT_USER\Software\bcrypt
It adds the following registry entries:
HKEY_CURRENT_USER\Software\bcrypt
i = "7d9"
Dropping Routine
This backdoor drops the following files:
- %User Profile%\Application Data\bcrypt.html
- %System Root%\RECYCLER\S-1-5-21-0636360875-2094037254-701732380-5722\Desktop.ini
(Note: %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.. %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)
This report is generated via an automated analysis system.
SOLUTION
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
Identify and delete files detected as BKDR_AGENTT.DQ using either the Startup Disk or Recovery Console
Step 3
Delete this registry key
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_CURRENT_USER\Software
- bcrypt
Step 4
Delete this registry value
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 NT\CurrentVersion\Winlogon
- Taskman = "%System Root%\RECYCLER\S-1-5-21-0636360875-2094037254-701732380-5722\mwau.exe"
- In HKEY_CURRENT_USER\Software\bcrypt
- i = "7d9"
Step 5
Search and delete these files
- %User Profile%\Application Data\bcrypt.html
- %System Root%\RECYCLER\S-1-5-21-0636360875-2094037254-701732380-5722\Desktop.ini
Step 6
Search and delete these folders
- %System Root%\RECYCLER
- %System Root%\RECYCLER\S-1-5-21-0636360875-2094037254-701732380-5722
Step 7
Scan your computer with your Trend Micro product to delete files detected as BKDR_AGENTT.DQ. 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.
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