BKDR_BUTERAT.YHK

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.

File Size: 990,208 bytes

File Type: EXE

Memory Resident: Yes

Initial Samples Received Date: 11 Feb 2016

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 creates the following folders:

%User Profile%\Application Data\LSinglePro
%User Profile%\LSinglePro\Temporary Internet Files
%User Profile%\LSinglePro\TFExecuter4
%User Profile%\LSinglePro\cookies
%User Profile%\cookies\61362320
%User Profile%\cookies\58688588
%User Profile%\cookies\59591878
%User Profile%\cookies\56459203

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)

Autostart Technique

This backdoor adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
GuaZhuan = "{malware path and file name} -autorun "

Other System Modifications

This backdoor modifies the following file(s):

%Windows%\inf\intl.PNF

(Note: %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.)

It deletes the following files:

%User Profile%\LSinglePro\log.txt

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)

It deletes the following folders:

%System Root%\Temporary Files
%User Profile%\LSinglePro\Temporary Internet Files
%User Profile%\LSinglePro\cookies

(Note: %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.. %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)

It adds the following registry keys:

HKEY_CURRENT_USER\Software\CHtmlDialog\
International

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\International\CpMRU

It adds the following registry entries:

HKEY_CURRENT_USER\Software\CHtmlDialog\
International
AutoDetect = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\International\CpMRU
Enable = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\International\CpMRU
Size = "a"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\International\CpMRU
InitHits = "64"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\International\CpMRU
Factor = "14"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\International
W2KLpk = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\International
W2KLpk = "0"

Dropping Routine

This backdoor drops the following files:

%User Profile%\TFExecuter4\HLR_cfg.ini.bak
%User Profile%\TFExecuter4\SearchEngine.ini.bak
%User Profile%\TFExecuter4\GlobalConfig.ini.bak
%User Profile%\LSinglePro\blhash.dat.bak
%User Profile%\LSinglePro\runtask.dat.bak
%User Profile%\LSinglePro\bts.dat.bak
%User Profile%\LSinglePro\bts_tm.dat.bak
%User Profile%\LSinglePro\bts_tmh.dat.bak
%User Profile%\LSinglePro\bl.dat.bak

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)

Other Details

This backdoor connects to the following possibly malicious URL:

http://ap4.{BLOCKED}ngbao.cn
http://ap4.{BLOCKED}ngbao.cn/redirect/CFGUpdate?{random characters}
http://ap4.{BLOCKED}ngbao.cn/{random path}
http://ap4.{BLOCKED}ngbao.cn/clt/config/cfg_6.5.ini?{random characters}
http://cltres.{BLOCKED}ngbao.cn/clt/config/cfg_6.5.ini?{random characters}
http://cltres.{BLOCKED}ngbao.cn/clt/config/SearchEngine_6.5.ini?{random characters}
http://cltres.{BLOCKED}ngbao.cn/clt/config/GlobalConfig_6.5.ini?{random characters}
http://cltres.{BLOCKED}ngbao.cn/as/down/clt/config/blhash_6.5.dat?{random characters}
http://ap4.{BLOCKED}ngbao.cn/as/down/clt/config/blhash_6.5.dat?{random characters}
http://cltres.{BLOCKED}ngbao.cn/redirect/CFGUpdate?{random characters}
http://ap4.{BLOCKED}ngbao.cn/clt/config/runtask_6.5.dat?{random characters}
http://ap2.{BLOCKED}0.com
http://cltres.{BLOCKED}ngbao.cn/clt/config/runtask_6.5.dat?{random characters}
http://ap4.{BLOCKED}ngbao.cn/as/down/clt/config/bts.dat?{random characters}
http://ap4.{BLOCKED}ngbao.cn/as/down/clt/config/bts_tm.dat?{random characters}
http://cltres.{BLOCKED}ngbao.cn/as/down/clt/config/bts_tm.dat?{random characters}
http://ap4.{BLOCKED}ngbao.cn/as/down/clt/config/bts_tmh.dat?{random characters}
http://ap4.{BLOCKED}ngbao.cn/clt/config/bl_6.5.dat?{random characters}
http://cltres.{BLOCKED}ngbao.cn/clt/config/bl_6.5.dat?{random characters}
http://ap2.{BLOCKED}ngbao.cn
{BLOCKED}.110.5
{BLOCKED}.219.243
{BLOCKED}0.136.220
{BLOCKED}208.198
{BLOCKED}.1.2
{BLOCKED}.251.251
{BLOCKED}7.42.34
{BLOCKED}226.50
{BLOCKED}.109.136
{BLOCKED}1.7.190
{BLOCKED}8.23.144
{BLOCKED}3.229.5
{BLOCKED}7.216.183
{BLOCKED}3.160.200
{BLOCKED}3.234.21
{BLOCKED}3.237.3
{BLOCKED}9.134.224
{BLOCKED}.139.142
{BLOCKED}.28.96
{BLOCKED}.38.32
{BLOCKED}.221.145
{BLOCKED}6.22.240
{BLOCKED}.13.182
{BLOCKED}9.39.179
{BLOCKED}0.121.64
{BLOCKED}.36.106

This report is generated via an automated analysis system.

Minimum Scan Engine: 9.8

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

Restart in Safe Mode

[ Learn More ]

Step 3

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_CURRENT_USER\Software\CHtmlDialog\
- International

In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\International
- CpMRU

Step 4

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
- GuaZhuan = "{malware path and file name} -autorun "

In HKEY_CURRENT_USER\Software\CHtmlDialog\International
- AutoDetect = "1"

In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\International\CpMRU
- Enable = "1"

In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\International\CpMRU
- Size = "a"

In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\International\CpMRU
- InitHits = "64"

In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\International\CpMRU
- Factor = "14"

In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\International
- W2KLpk = "1"

In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\International
- W2KLpk = "0"

Step 5

Search and delete these components

[ Learn More ]

There may be some components 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.

%User Profile%\TFExecuter4\HLR_cfg.ini.bak
%User Profile%\TFExecuter4\SearchEngine.ini.bak
%User Profile%\TFExecuter4\GlobalConfig.ini.bak
%User Profile%\LSinglePro\blhash.dat.bak
%User Profile%\LSinglePro\runtask.dat.bak
%User Profile%\LSinglePro\bts.dat.bak
%User Profile%\LSinglePro\bts_tm.dat.bak
%User Profile%\LSinglePro\bts_tmh.dat.bak
%User Profile%\LSinglePro\bl.dat.bak

Step 6

Search and delete these folders

[ Learn More ]

Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.

%User Profile%\Application Data\LSinglePro
%User Profile%\LSinglePro\Temporary Internet Files
%User Profile%\LSinglePro\TFExecuter4
%User Profile%\LSinglePro\cookies
%User Profile%\cookies\61362320
%User Profile%\cookies\58688588
%User Profile%\cookies\59591878
%User Profile%\cookies\56459203

To delete malware/grayware/spyware folders:

For Windows 2000, Windows XP, and Windows Server 2003:

Right-click Start then click Search... or Find..., depending on the version of Windows you are running.
In the File name* input box, type:

%User Profile%\Application Data\LSinglePro
%User Profile%\LSinglePro\Temporary Internet Files
%User Profile%\LSinglePro\TFExecuter4
%User Profile%\LSinglePro\cookies
%User Profile%\cookies\61362320
%User Profile%\cookies\58688588
%User Profile%\cookies\59591878
%User Profile%\cookies\56459203
In the Look In drop-down list, select My Computer, then press Enter.
Once located, select the folder then press SHIFT+DELETE to permanently delete the folder.
Repeat steps 2 to 4 for the remaining folders: %User Profile%\Application Data\LSinglePro
%User Profile%\LSinglePro\Temporary Internet Files
%User Profile%\LSinglePro\TFExecuter4
%User Profile%\LSinglePro\cookies
%User Profile%\cookies\61362320
%User Profile%\cookies\58688588
%User Profile%\cookies\59591878
%User Profile%\cookies\56459203

*Note: The file name input box title varies depending on the Windows version (e.g. Search for files or folders named or All or part of the file name.).

For Windows Vista, Windows 7, Windows Server 2008, Windows 8, Windows 8.1, and Windows Server 2012:

Open a Windows Explorer window.
- For Windows Vista, 7, and Server 2008 users, click Start>Computer.
- For Windows 8, 8.1, and Server 2012 users, right-click on the lower left corner of the screen, then click File Explorer.
In the Search Computer/This PC input box, type:
%User Profile%\Application Data\LSinglePro
%User Profile%\LSinglePro\Temporary Internet Files
%User Profile%\LSinglePro\TFExecuter4
%User Profile%\LSinglePro\cookies
%User Profile%\cookies\61362320
%User Profile%\cookies\58688588
%User Profile%\cookies\59591878
%User Profile%\cookies\56459203
Once located, select the file then press SHIFT+DELETE to permanently delete the folder.
Repeat steps 2-3 for the remaining folders: %User Profile%\Application Data\LSinglePro
%User Profile%\LSinglePro\Temporary Internet Files
%User Profile%\LSinglePro\TFExecuter4
%User Profile%\LSinglePro\cookies
%User Profile%\cookies\61362320
%User Profile%\cookies\58688588
%User Profile%\cookies\59591878
%User Profile%\cookies\56459203

*Note: Read the following Microsoft page if these steps do not work on Windows 7.

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_BUTERAT.YHK. 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 8

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.

%Windows%\inf\intl.PNF

Step 9

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.

%User Profile%\LSinglePro\log.txt

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