TSPY_YOMYAEL.C


 ALIASES:

Trojan:Win32/Skeeyah.A!bit (Microsoft); Trojan Horse (Symantec); Backdoor.Win32.Androm.hble (Kaspersky); Trojan.Win32.Generic!BT (Sunbelt); Trojan horse Inject2.CGGA (AVG)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 REPORTED INFECTION:
 SYSTEM IMPACT RATING:
 INFORMATION EXPOSURE:

  • Threat Type: Spyware

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW


This spyware 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

File Size:

96,256 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

25 Jun 2015

Arrival Details

This spyware 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 spyware creates the following folders:

  • %User Temp%\Hs_

(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 spyware adds the following registry entries to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
DD9B9BXR = "{malware path and file name}"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
syotom = "%System%\attrib.exe"

Other System Modifications

This spyware adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
Windows Script\Settings

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
%System%\attrib.exe = "%System%\attrib.exe:*:Enabled:Sevsl"

HKEY_CURRENT_USER\Software\Microsoft\
Windows Script\Settings
JITDebug = "0"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Tcpip\Parameters\
Interfaces\{706C9A23-9058-4780-9179-0EE8467AACB4}
NameServer = "127.0.0.1,127.0.0.1"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Tcpip\Parameters\
Interfaces\{DAE77112-CC69-4B9B-B0BB-8B4C380B15D1}
NameServer = "127.0.0.1,127.0.0.1"

It modifies the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
Start Page = "www.naver.com"

(Note: The default value data of the said registry entry is http://www.microsoft.com/isapi/redir.dll?prd=ie&pver=6&ar=msnhome.)

Dropping Routine

This spyware drops the following files:

  • %User Temp%\58b8052567ade6540adf05ec8d813970.zip

(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.)

Other Details

This spyware connects to the following possibly malicious URL:

  • http://{BLOCKED}8.242.154
  • {BLOCKED}0.1
  • {BLOCKED}.243.35

This report is generated via an automated analysis system.

  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

Restart in Safe Mode

[ Learn More ]

Step 3

Delete this registry key

[ 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_CURRENT_USER\Software\Microsoft\Windows Script
    • Settings

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\Run
    • DD9B9BXR = "{malware path and file name}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • syotom = "%System%\attrib.exe"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
    • %System%\attrib.exe = "%System%\attrib.exe:*:Enabled:Sevsl"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows Script\Settings
    • JITDebug = "0"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Tcpip\Parameters\Interfaces\{706C9A23-9058-4780-9179-0EE8467AACB4}
    • NameServer = "127.0.0.1,127.0.0.1"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Tcpip\Parameters\Interfaces\{DAE77112-CC69-4B9B-B0BB-8B4C380B15D1}
    • NameServer = "127.0.0.1,127.0.0.1"

Step 5

Restore these modified registry values

[ Learn More ]

Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out this Microsoft article first before modifying your computer's registry.

  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
    • From: Start Page = "www.naver.com"
      To: Start Page = ""http://www.microsoft.com/isapi/redir.dll?prd=ie&pver=6&ar=msnhome""

Step 6

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%\58b8052567ade6540adf05ec8d813970.zip

Step 7

Search and delete this folder

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • %User Temp%\Hs_

Step 8

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TSPY_YOMYAEL.C. 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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