TROJ_HIDFILE.AB
Trojan:Win32/Rotinom.B (Microsoft); Generic.dx!vik (McAfee); Trojan.Gen (Symantec); Trojan.Win32.Agent2.crpo (Kaspersky); Trojan.Win32.Rotinom.b (v) (Sunbelt); Backdoor.Agent.AASN (FSecure)
Windows 2000, Windows XP, Windows Server 2003
![](/vinfo/imgFiles/legend.jpg)
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.
TECHNICAL DETAILS
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:
- %Application Data%\start\update.exe
(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Windows\Profiles\{user name}\Application Data on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Application Data on Windows NT, and C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003.)
It creates the following folders:
- %Application Data%\S-1-5-31-1286970278978-5713669491-166975984-320
- %Application Data%\S-1-5-31-1286970278978-5713669491-166975984-320\dmc
- %Application Data%\S-1-5-31-1286970278978-5713669491-166975984-320\tlsr
- %Application Data%\S-1-5-31-1286970278978-5713669491-166975984-320\Rotinom
- %Application Data%\start
- %System Root%\013a9ab56965a330a57ff6421caa0702672a12ee_cb90b93633bc4241942efe8dd933\
(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Windows\Profiles\{user name}\Application Data on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Application Data on Windows NT, and C:\Documents and Settings\{user name}\Local Settings\Application Data 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.)
Other System Modifications
This Trojan modifies the following registry entries:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
Hidden = 2
(Note: The default value data of the said registry entry is 2.)
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
HideFileExt = 1
(Note: The default value data of the said registry entry is 1.)
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Shell Folders
Startup = "%Application Data%\start"
(Note: The default value data of the said registry entry is %User Startup%.)
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
User Shell Folders
Startup = "%Application Data%\start"
(Note: The default value data of the said registry entry is %USERPROFILE%\Start Menu\Programs\Startup.)
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
Restore this modified 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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
- From: Hidden=2
To: Hidden=2
- From: Hidden=2
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
- From: HideFileExt=1
To: HideFileExt=1
- From: HideFileExt=1
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders
- From: Startup="%Application Data%\start"
To: Startup=%User Startup%
- From: Startup="%Application Data%\start"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders
- From: Startup="%Application Data%\start"
To: Startup=%USERPROFILE%\Start Menu\Programs\Startup
- From: Startup="%Application Data%\start"
Step 3
Search and delete these folders
- %Application Data%\S-1-5-31-1286970278978-5713669491-166975984-320
- %Application Data%\S-1-5-31-1286970278978-5713669491-166975984-320\dmc
- %Application Data%\S-1-5-31-1286970278978-5713669491-166975984-320\tlsr
- %Application Data%\S-1-5-31-1286970278978-5713669491-166975984-320\Rotinom
- %Application Data%\start
- %System Root%\013a9ab56965a330a57ff6421caa0702672a12ee_cb90b93633bc4241942efe8dd933\
Step 4
Scan your computer with your Trend Micro product to delete files detected as TROJ_HIDFILE.AB. 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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