BKDR_TOFSEE.MN
Trojan horse Generic27.BTZY(AVG), W32/Buzus.AABA!tr(Fortinet), Trojan.Win32.Jorik(Ikarus), Trojan.Win32.Slenfbot.tw(Kaspersky), Backdoor:Win32/Tofsee.F(Microsoft), Trojan-FACW!7557A1FD9E4B(NAI), Win32/Injector.PUH trojan(NOD32), Trojan.Win32.Generic!BT(Sunbelt), Trojan.Jorik.IRCbot(VBA32), TR/Patched.Ren.Gen(Antivir)
Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)
![](/vinfo/imgFiles/legend.jpg)
Threat Type: Backdoor
Destructiveness: No
Encrypted: Yes
In the wild: Yes
OVERVIEW
Downloaded from the Internet, Dropped by other malware
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.
It does not have any information-stealing capability.
TECHNICAL DETAILS
TCP Port 80 (HTTP), Port 25 (Simple Mail Transfer)
619,008 bytes
EXE
Yes
11 Oct 2013
Compromises system security, Connects to URLs/IPs, Drops files
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 and executes the following files:
- %User Temp%\{random number}.bat
(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)
It drops the following copies of itself into the affected system:
- %User Profile%\{random file name}.exe
(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 injects codes into the following process(es):
- %System%\svchost.exe
(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)
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
MSConfig = ""%User Profile%\{random file name}.exe" /r"
Other System Modifications
This backdoor modifies the following registry entries:
HKEY_CURRENT_USER\Software\Microsoft\
CurrentVersion\Internet Settings\ZoneMap
ProxyBypass = "1"
(Note: The default value data of the said registry entry is "0".)
HKEY_CURRENT_USER\Software\Microsoft\
CurrentVersion\Internet Settings\ZoneMap
IntranetName = "1"
(Note: The default value data of the said registry entry is "0".)
HKEY_CURRENT_USER\Software\Microsoft\
CurrentVersion\Internet Settings\ZoneMap
UNCAsIntranet = "1"
(Note: The default value data of the said registry entry is "0".)
HKEY_CURRENT_USER\Software\Microsoft\
CurrentVersion\Internet Settings\ZoneMap
AutoDetect = "1"
(Note: The default value data of the said registry entry is "1".)
Backdoor Routine
This backdoor connects to the following URL(s) to send and receive commands from a remote malicious user:
- {BLOCKED}bgddtyh.biz
- {BLOCKED}hbyrukl.ch
As of this writing, the said servers are currently inaccessible.
Information Theft
This backdoor does not have any information-stealing capability.
Other Details
This backdoor connects to the following URL(s) to check for an Internet connection:
- microsoft.com
- yahoo.com
- google.com
NOTES:
The dropped .BAT file is executed to delete its initial copy and the .BAT file the malware created.
It creates a new process for svchost.exe into which it injects its malicious routines.
This backdoor has the capability to send or forward SMTP traffic to the mail servers of the following:
- mxs.mail.ru
- yahoo.com
- google.com
- inbound.protection.outlook.com
SOLUTION
9.300
10.334.01
11 Oct 2013
10.335.00
11 Oct 2013
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
Step 3
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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
- MSConfig = ""%User Profile%\{random file name}.exe" /r"
- MSConfig = ""%User Profile%\{random file name}.exe" /r"
Step 4
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\CurrentVersion\Internet Settings\ZoneMap
- From: ProxyBypass = "1"
To: ProxyBypass = "0"
- From: ProxyBypass = "1"
- In HKEY_CURRENT_USER\Software\Microsoft\CurrentVersion\Internet Settings\ZoneMap
- From: IntranetName = "1"
To: IntranetName = "0"
- From: IntranetName = "1"
- In HKEY_CURRENT_USER\Software\Microsoft\CurrentVersion\Internet Settings\ZoneMap
- From: UNCAsIntranet = "1"
To: UNCAsIntranet = "0"
- From: UNCAsIntranet = "1"
- In HKEY_CURRENT_USER\Software\Microsoft\CurrentVersion\Internet Settings\ZoneMap
- From: AutoDetect = "1"
To: AutoDetect = "1" (Default), modifies if "0"
- From: AutoDetect = "1"
Step 5
Search and delete this file
- %User Profile%\{random file name}.exe
Step 6
Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_TOFSEE.MN. 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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