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BKDR_SKYTIC.AA

September 15, 2015
 Analysis by: David John Agni
 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet

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 executes commands from a remote malicious user, effectively compromising the affected system. It connects to a website to send and receive information.

  TECHNICAL DETAILS

File Size:

1,412,096 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

09 Mar 2014

Payload:

Connects to URLs/IPs, Steals information

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 the following files:

  • %User Temp%\token.txt - generatad ID

(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.)

It drops and executes the following files:

  • %User Temp%\Temp\IXP000.TMP\INSTAL~2.EXE - non malicious Flash Player Installer to trick the user.
  • %User Temp%\StickyNotes.exe - detected as BKDR_SKYTIC.AA

(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.)

Autostart Technique

This backdoor adds the following registry entries to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\RunOnce
Windows = "%User Temp%\StickyNotes.exe"

Backdoor Routine

This backdoor executes the following commands from a remote malicious user:

  • Download or Upload file
  • Perform Remote Shell Command

It connects to the following websites to send and receive information:

  • {BLOCKED}.{BLOCKED}.225.243:443
  • {BLOCKED}.{BLOCKED}.225.243:8080
  • {BLOCKED}.{BLOCKED}.225.243:2100
  • {BLOCKED}.{BLOCKED}.225.243:2200
  • http://www.{BLOCKED}lash11.com/index.php?a=ila
  • http://www.{BLOCKED}lash11.com/index.php?a=b

Dropping Routine

This backdoor drops the following file(s), which it uses for its keylogging routine:

  • %User Temp%\154AFF54BCb343e5bfdabc054ab45d67.tmp

(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.)

It drops the following files wherein it saves the information it gathers:

  • %User Temp%\HaSc.txt
  • %User Temp%\HaSc.zip - where it list all the found files, directories, and installed devices
  • %User Temp%\dA5F54D1A1.tmp - filename use for screenshots
  • %User Profile%\ApplicatiLocal\Temp\gcdata.txt - Browser Login Credentials

(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.. %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.)

Information Theft

This backdoor gathers the following data:

  • All installed devices, directory and files of the infected system
  • Steal Google Chrome Browser login credentials
  • Keystrokes

NOTES:

This backdoor checks the current active window name and takes screenshots if one of the following strings are found:

  • bank
  • email
  • government
  • log in
  • login
  • paypal
  • sign in
  • signin

  SOLUTION

Minimum Scan Engine:

9.750

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

Identify and terminate files detected as BKDR_SKYTIC.AA

[ Learn More ]
  1. 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.
  2. 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.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

Step 4

Delete this registry value

[ Learn More ]

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\RunOnce
    • Windows = "%User Temp%\StickyNotes.exe"

Step 5

Search and delete this file

[ Learn More ]
There may be some files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.
  • %User Temp%\token.txt
  • %User Temp%\154AFF54BCb343e5bfdabc054ab45d67.tmp
  • %User Profile%\ApplicatiLocal\Temp\gcdata.txt
  • %User Temp%\HaSc.txt
  • %User Temp%\HaSc.zip
  • %User Temp%\dA5F54D1A1.tmp

Step 6

Scan your computer with your Trend Micro product to delete files detected as BKDR_SKYTIC.AA. 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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