TROJ_CROWTI.ER
Ransom:Win32/Crowti (Microsoft)
Windows
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.
It deletes the initially executed copy of itself.
TECHNICAL DETAILS
EXE
Yes
17 Mar 2015
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%\{8 Random Value}\{8 Random Value}.exe
- %Application Data%\{8 Random Value}.exe
(Note: %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.. %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming 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:
- %System Root%\{8 Random Value}
(Note: %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.)
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
{8 Random Value} = "%Application Data%\{8 Random Value}.exe"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{First 7 Characters of {8 Random Value}} = "%System Root%\{8 Random Value}\{8 Random Value}.exe"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\RunOnce
*{Second to the Sixth Characters {8 Random Value}} = "%System Root%\{8 Random Value}\{8 Random Value}.exe"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\RunOnce
*{Last Seven Characters of {8 Random Value}} = "%Application Data%\{8 Random Value}.exe"
It drops the following file(s) in the Windows User Startup folder to enable its automatic execution at every system startup:
- %User Startup%\{8 Random Value}.exe
(Note: %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup.)
Other System Modifications
This Trojan adds the following registry keys:
HKEY_CURRENT_USER\Software\{Random Value}
It adds the following registry entries:
HKEY_CURRENT_USER\Software\{Random Value}
0v = "?[DEFAULT] BASEURL....."
HKEY_CURRENT_USER\Software\{Random Value}
1u = "?What happened to your files ?........"
HKEY_CURRENT_USER\Software\{Random Value}\
{Random}
{Value} = "{List of encrypted files}"
Other Details
This Trojan connects to the following possibly malicious URL:
- {BLOCKED}rfband.info/img1.php?{Random String}
- {BLOCKED}ian.com/img1.php?{Random String}
- {BLOCKED}soft.com/img1.php?{Random String}
- {BLOCKED}eeasset.com/img5.php?{Random String}
- {BLOCKED}xbjx.com/img2.php?{Random String}
- {BLOCKED}iet.com/img1.php?{Random String}
- {BLOCKED}.com/img3.php?{Random String}
- {BLOCKED}amuslim-online.com/img5.php?{Random String}
- {BLOCKED}kan-guvenlik.com/img4.php?{Random String}
- {BLOCKED}italmd.com/img1.php?{Random String}
- {BLOCKED}us/img4.php?{Random String}
- {BLOCKED}biaunited.com/img5.php?{Random String}
- {BLOCKED}nwohnungen-diana.com/img1.php?{Random String}
- {BLOCKED}ade.com/img2.php?{Random String}
- {BLOCKED}g8.com/img5.php?{Random String}
- {BLOCKED}ndtile.net/img3.php?{Random String}
- {BLOCKED}world.com/img3.php?{Random String}
- {BLOCKED}salaria.org/img5.php?{Random String}
- {BLOCKED}a-ng.com/img5.php?{Random String}
- {BLOCKED}azateonline.com/img3.php?{Random String}
- {BLOCKED}cyber.com/img2.php?{Random String}
- {BLOCKED}m.com/img4.php?{Random String}
- {BLOCKED}09.com/img2.php?{Random String}
- {BLOCKED}chae.com/img4.php?{Random String}
- {BLOCKED}loosphoto.com/img4.php?{Random String}
- {BLOCKED}.com/img3.php?{Random String}
- {BLOCKED}hurch.com/img2.php?{Random String}
- {BLOCKED}profreshional.com/img1.php?{Random String}
It deletes the initially executed copy of itself
NOTES:
It encrypts files with certain extensions in the affected system hard drive.
It drops the following files to all folders where files are encrypted:
- HELP_DECRYPT.HTML
- HELP_DECRYPT.TXT
- HELP_DECRYPT.PNG
- HELP_DECRYPT
SOLUTION
9.750
11.556.03
17 Mar 2015
11.557.00
18 Mar 2015
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
Search and delete this file
- %Application Data%\{8 Random Value}.exe
- %User Startup%\{8 Random Value}.exe
Step 5
Search and delete these folders
- %System Root%\{8 Random Value}
Step 6
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
- {8 Random Value} = "%Application Data%\{8 Random Value}.exe"
- {8 Random Value} = "%Application Data%\{8 Random Value}.exe"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
- {First 7 Characters of {8 Random Value}} = "%System Root%\{8 Random Value}\{8 Random Value}.exe"
- {First 7 Characters of {8 Random Value}} = "%System Root%\{8 Random Value}\{8 Random Value}.exe"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\RunOnce
- *{Second to the Sixth Characters {8 Random Value}} = "%System Root%\{8 Random Value}\{8 Random Value}.exe"
- *{Second to the Sixth Characters {8 Random Value}} = "%System Root%\{8 Random Value}\{8 Random Value}.exe"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\RunOnce
- *{Last Seven Characters of {8 Random Value}} = "%Application Data%\{8 Random Value}.exe"
- *{Last Seven Characters of {8 Random Value}} = "%Application Data%\{8 Random Value}.exe"
Step 7
Delete this registry key
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
- {Random Value}
- {Random Value}
Step 8
Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_CROWTI.ER. 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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