TROJ_KRYPTK.SMCR
Sophos: Mal/EncPk-ZV
Windows 2000, Windows XP, Windows Server 2003
Threat Type: Trojan
Destructiveness: No
Encrypted: Yes
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
150,016 bytes
EXE
Yes
20 Jun 2011
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:
- %System Root%\Recycle.Bin\B6232F3A{random}.exe
(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)
Autostart Technique
This Trojan adds the following registry entries to enable its automatic execution at every system startup:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{random} = "%System Root%\Recycle.Bin\B6232F3A{random}.exe /q"
Other System Modifications
This Trojan adds the following registry entries as part of its installation routine:
HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\PhishingFilter
EnabledV8 = "0"
HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\PhishingFilter
ShownServiceDownBalloon = "0"
HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Recovery
ClearBrowsingHistoryOnExit = "0"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
ProxyHttp1.1 = "1"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
WarnOnPostRedirect = "0"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
WarnOnIntranet = "0"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
GlobalUserOffline = "0"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
Zones\0
1409 = "3"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
Zones\1
1409 = "3"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
Zones\2
1409 = "3"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
Zones\3
1409 = "3"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
Zones\4
1409 = "3"
It modifies the following registry entries:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
WarnOnPost = "00 00 00 00"
(Note: The default value data of the said registry entry is 01 00 00 00 .)
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
Lockdown_Zones\1
1406 = "0"
(Note: The default value data of the said registry entry is 1.)
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
Lockdown_Zones\3
1406 = "0"
(Note: The default value data of the said registry entry is 3.)
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
Lockdown_Zones\4
1406 = "0"
(Note: The default value data of the said registry entry is 3.)
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
Zones\0
1609 = "0"
(Note: The default value data of the said registry entry is 1.)
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
Zones\1
1406 = "0"
(Note: The default value data of the said registry entry is 1.)
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
Zones\1
1609 = "0"
(Note: The default value data of the said registry entry is 1.)
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
Zones\2
1609 = "0"
(Note: The default value data of the said registry entry is 1.)
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
Zones\3
1406 = "0"
(Note: The default value data of the said registry entry is 3.)
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
Zones\3
1609 = "0"
(Note: The default value data of the said registry entry is 1.)
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
Zones\4
1406 = "0"
(Note: The default value data of the said registry entry is 3.)
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
Zones\4
1609 = "0"
(Note: The default value data of the said registry entry is 1.)
SOLUTION
8.900
8.236.06
20 Jun 2011
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
Identify and terminate files detected as TROJ_KRYPTK.SMCR
- Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
- If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
- If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.
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
- {random} = "%System Root%\Recycle.Bin\B6232F3A{random}.exe /q"
- {random} = "%System Root%\Recycle.Bin\B6232F3A{random}.exe /q"
- In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\PhishingFilter
- EnabledV8 = "0"
- EnabledV8 = "0"
- In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\PhishingFilter
- ShownServiceDownBalloon = "0"
- ShownServiceDownBalloon = "0"
- In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Recovery
- ClearBrowsingHistoryOnExit = "0"
- ClearBrowsingHistoryOnExit = "0"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
- ProxyHttp1.1 = "1"
- ProxyHttp1.1 = "1"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
- WarnOnPostRedirect = "0"
- WarnOnPostRedirect = "0"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
- WarnOnIntranet = "0"
- WarnOnIntranet = "0"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
- GlobalUserOffline = "0"
- GlobalUserOffline = "0"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\0
- 1409 = "3"
- 1409 = "3"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\1
- 1409 = "3"
- 1409 = "3"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\2
- 1409 = "3"
- 1409 = "3"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\3
- 1409 = "3"
- 1409 = "3"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\4
- 1409 = "3"
- 1409 = "3"
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\Windows\CurrentVersion\Internet Settings
- From: WarnOnPost =
To: WarnOnPost = "01 00 00 00"
- From: 1406 =
To: 1406 = "1"
- From: 1406 =
To: 1406 = "3"
- From: 1406 =
To: 1406 = "3"
- From: 1609 =
To: 1609 = "1"
- From: 1406 =
To: 1406 = "1"
- From: 1609 =
To: 1609 = "1"
- From: 1609 =
To: 1609 = "1"
- From: 1406 =
To: 1406 = "3"
- From: 1609 =
To: 1609 = "1"
- From: 1406 =
To: 1406 = "3"
- From: 1609 =
To: 1609 = "1"
Step 5
Scan your computer with your Trend Micro product to delete files detected as TROJ_KRYPTK.SMCR. 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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