WORM_SKYSTLR.A
Virus:Win32/Sality.gen!enc (Microsoft); Virus.Win32.Sality.q, (Kaspersky); W32.Sality.U (Symantec);
Windows
Threat Type: Worm
Destructiveness: No
Encrypted: Yes
In the wild: Yes
OVERVIEW
Downloaded from the Internet, Dropped by other malware
This worm arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.
It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.
It modifies the affected system's HOSTS files. This prevents users from accessing certain websites.
TECHNICAL DETAILS
708096 bytes
EXE
Yes
Modifies HOSTS file, Terminates processes, Steals information
Arrival Details
This worm arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.
Autostart Technique
This worm adds the following registry entries to enable its automatic execution at every system startup:
HKEY_CURRENT_USER\Software\Microsoft\
Windows \CurrentVersion\Run
SystemDLL.MICROSOFT = “{malware path}\{malware filename}”
HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows \CurrentVersion\Run
SystemDLL.MICROSOFT = “{malware path}\{malware filename}”
Other System Modifications
This worm adds the following registry entries:
HKEY_CURRENT_USER\Software\Microsoft\
Windows \CurrentVersion\Policies\
System"
DisableTaskMgr = "1"
HKEY_CURRENT_USER\Software\Microsoft\
Windows \CurrentVersion\Explorer\
Advanced
Hidden = "0"
Propagation
This worm drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.
The said .INF file contains the following strings:
[autorun]
open={Drive Letter}:\HDDFile.com
shellexecute={Drive Letter}:\
It uses any of the following Simple Mail Transfer Protocol (SMTP) servers:
- smtp.gmail.com
Process Termination
This worm terminates the following processes if found running in the affected system's memory:
- anubis
- ashWebSv
- avgemc
- bdagent
- cpf
- avp
- keyscrambler
- mbam
- egui
- npfmsg
- ollydbg
- outpost
- vpcmapvmsrvc
- wireshark
HOSTS File Modification
This worm modifies the affected system's HOSTS files to prevent a user from accessing the following websites:
- www.virustotal.com
- www.bitdefender.com
- www.virusscan.jotti.org
- www.scanner.novirusthanks.org
- www.chip.de
- www.vscan.novirusthanks.org
- www.avira.de
- www.avast.com
Stolen Information
The stolen information is saved in the following file:
- %User Temp%\firefox.txt
- %User Temp%\data.txt
- %User Temp%\mess.txt
- %User Temp%\astlog.txt
- %User Temp%\mailpv.txt
- %User Temp%\RouterPassView.txt
- %User Temp%\iepv.txt
- %User Temp%\OperPassView.txt
- %User Temp%\ChromePass.txt
(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp 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.)
NOTES:
This worm is infected with PE_SALITY.
It drops the following copy of itself on other drives aside from %SystemRoot%:
- {Drive Letter}:\HDDFile.com
It retrieves the following information from the system:
- passwords covered by asterisks on open windows
- Chrome usernames and passwords
- Dial-up usernames and passwords
- Firefox usernames and passwords
- IE usernames and passwords
- Opera usernames and passwords
- router usernames and passwords
- account details from the following email clients:
Outlook Express
Microsoft Outlook 2000
Microsoft Outlook 2002/2003/2007/2010
Windows Mail
Windows Live Mail
IncrediMail
Eudora
Netscape 6.x/7.x
Mozilla Thunderbird
Group Mail Free
Yahoo! Messenger application
MSN/Windows/Live Messenger application
Gmail Notifier application
Google Desktop
Google Talk - passwords from the following instant messaging applications:
MSN Messenger
Windows Messenger
Windows Live Messenger
Yahoo Messenger
Google Talk
ICQ Lite 4.x/5.x/2003
AOL Instant Messenger
AIM 6.x
AIM Pro
Trillian
Trillian Astra
Miranda
GAIM/Pidgin
MySpace IM
PaltalkScene
Digsby
SOLUTION
9.750
11.938.04
24 Sep 2015
11.939.00
25 Sep 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
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
- SystemDLL.MICROSOFT = “{malware path}\{malware filename}”
- SystemDLL.MICROSOFT = “{malware path}\{malware filename}”
- In HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
- SystemDLL.MICROSOFT = “{malware path}\{malware filename}”
- SystemDLL.MICROSOFT = “{malware path}\{malware filename}”
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\System"
- DisableTaskMgr = "1"
- DisableTaskMgr = "1"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
- Hidden = "0"
- Hidden = "0"
Step 5
Search and delete AUTORUN.INF files created by WORM_SKYSTLR.A that contain these strings
- [autorun]
- open={Drive Letter}:\HDDFile.com
- shellexecute={Drive Letter}:\
Step 6
Search and delete this file
- %User Temp%\firefox.txt
- %User Temp%\data.txt
- %User Temp%\mess.txt
- %User Temp%\astlog.txt
- %User Temp%\mailpv.txt
- %User Temp%\RouterPassView.txt
- %User Temp%\iepv.txt
- %User Temp%\OperPassView.txt
- %User Temp%\ChromePass.txt
Step 7
Remove these strings added by the malware/grayware/spyware in the HOSTS file
- 127.0.0.1 www.virustotal.com
- 127.0.0.1 www.bitdefender.com
- 127.0.0.1 www.virusscan.jotti.org
- 127.0.0.1 www.scanner.novirusthanks.org
- 127.0.0.1 www.chip.de
- 127.0.0.1 www.vscan.novirusthanks.org
- 127.0.0.1 www.avira.de
- 127.0.0.1 www.avast.com
Step 8
Restart in normal mode and scan your computer with your Trend Micro product for files detected as WORM_SKYSTLR.A. 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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