RANSOM_CRYPTLOCK.DLFLUM
Ransom:Win32/Teerac.A (Microsoft)
Windows
![](/vinfo/imgFiles/legend.jpg)
Threat Type: Trojan
Destructiveness: No
Encrypted: Yes
In the wild: Yes
OVERVIEW
Downloaded from the Internet, Dropped by other malware
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.
It modifies the Internet Explorer Zone Settings.
It connects to certain websites to send and receive information. However, as of this writing, the said sites are inaccessible.
TECHNICAL DETAILS
239,685 bytes
EXE
Yes
14 May 2016
Encrypts files, Connects to URLs/IPs, Displays message/message boxes
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:
- %Windows%\{Random Malware Filename}.exe
(Note: %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.)
It drops the following component file(s):
- %All Users Profile%\Application Data\{random folder name}\{random file name1}
- %All Users Profile%\Application Data\{random folder name}\{random file name3}
- %All Users Profile%\Application Data\{random folder name}\{random file name2}
(Note: %All Users Profile% is the All Users folder, where it usually is C:\Documents and Settings\All Users on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)
It creates the following folders:
- %All Users Profile%\Application Data\{random folder name}
(Note: %All Users Profile% is the All Users folder, where it usually is C:\Documents and Settings\All Users on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)
It injects codes into the following process(es):
- explorer.exe
Autostart Technique
This Trojan adds the following registry entries to enable its automatic execution at every system startup:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
{random} = "%Windows%\{Random Malware Filename}.exe"
Other System Modifications
This Trojan adds the following registry keys:
HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Windows Messaging Subsystem
HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Windows Messaging Subsystem\
Profiles
It adds the following registry entries:
HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\PhishingFilter
EnabledV8 = 0
HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\PhishingFilter
EnabledV9 = 0
Web Browser Home Page and Search Page Modification
This Trojan modifies the Internet Explorer Zone Settings.
Other Details
This Trojan connects to the following website to send and receive information:
- https://bemopron.{BLOCKED}alowe.org/topic.php
- https://{BLOCKED}er.com/topic.php
It encrypts files with the following extensions:
- .accdb
- .accdb
- .accde
- .accde
- .ade
- .adp
- .asc
- .asp
- .csv
- .cub
- .cub
- .dbf
- .doc
- .doc
- .docm
- .docm
- .docx
- .docx
- .dot
- .dot
- .dotm
- .dotx
- .dotx
- .dqy
- .dsn
- .htm
- .htm
- .htm*
- .html
- .html
- .iqy
- .mdb
- .mdb
- .mdb
- .mde
- .mde
- .mht
- .mht
- .mhtml
- .odc
- .ols
- .oqy
- .oqy
- .pab
- .prn
- .rqy
- .rtf
- .rtf
- .tab
- .txt
- .udl
- .uxdc
- .wdb
- .wj?
- .wk?
- .xls
- .xlsb
- .xlsm
- .xlsx
- .xsd
- .xsl
- .xslt
It renames encrypted files using the following names:
- {Original Filename}.encrypted
It does the following:
- It deletes shadow copies by executing the following command:
- vssadmin.exe Delete Shadows /All /Quiet
However, as of this writing, the said sites are inaccessible.
SOLUTION
9.800
12.902.03
16 Nov 2016
12.903.00
17 Nov 2016
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
Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.
Step 3
Restart in Safe Mode
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\CurrentVersion\Run
- {random} = "%Windows%\{Random Malware Filename}.exe"
- {random} = "%Windows%\{Random Malware Filename}.exe"
- In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\PhishingFilter
- EnabledV8 = 0
- EnabledV8 = 0
- In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\PhishingFilter
- EnabledV9 = 0
- EnabledV9 = 0
Step 5
Search and delete these folders
- %All Users Profile%\Application Data\{random folder name}
Step 6
Reset Internet security settings
Step 7
Restart in normal mode and scan your computer with your Trend Micro product for files detected as RANSOM_CRYPTLOCK.DLFLUM. 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 encrypted files from backup.
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