Threat Encyclopedia

TSPY_BANKER.YYSI

Publish date: December 15, 2014

ALIASES:

RDN/PWS-Banker!dn (McAfee), a variant of Win32/Spy.Banker.AAXV (ESET), W32/Banker.AAXV!tr.pws (Fortinet)

PLATFORM:

Windows

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

  • Threat Type:Spyware

  • Destructiveness:No

  • Encrypted: Yes

  • In the wild: Yes

OVERVIEW

Infection Channel:

Downloaded from the Internet


This threat is related to banking Trojans targeting South Korean banks that used Pinterest as their command and control (C&C) channel.

To get a one-glance comprehensive view of the behavior of this Spyware, refer to the Threat Diagram shown below.

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.

It modifies the Internet Explorer Zone Settings.

TECHNICAL DETAILS

File Size:

Varies

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

04 Dec 2014

Payload:

Connects to URLs/IPs, Steals information

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.

It may be downloaded from the following remote site(s):

  • http://{BLOCKED}e.co.kr/mm/sun.exe
  • http://www.{BLOCKED}e.co.kr/mm/sun.exe
  • http://{BLOCKED}ne.co.kr/data/1.exe
  • http://{BLOCKED}.{BLOCKED}.23.149/pop/pop/1.html

This malware arrives via the following means:

  • compromised sites
  • exploit kits

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
MyKB = "{malware path and filename}"

Other System Modifications

This spyware modifies the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
ProxyEnable = "1"

(Note: The default value data of the said registry entry is user-defined.)

Web Browser Home Page and Search Page Modification

This spyware modifies the Internet Explorer Zone Settings.

NOTES:

This spyware accesses the URL https://www.pinterest.com/pin/{BLOCKED}5416/ to retrieve the server IP address of fake login pages.

It monitors browsers to inject IFRAME to the following targeted webpages once accessed by users:

  • http://banking.nonghyup.com
  • http://banking.shinhan.com
  • http://hanabank.com
  • http://kbstar.com
  • http://mybank.ibk.co.kr
  • http://v3clinic.ahnlab.com
  • http://wooribank.com
  • http://www.fcsc.kr
  • http://www.ibk.co.kr

Thus, users are then redirected to fake websites hosted by the following servers:

  • {BLOCKED}.{BLOCKED}.245.120
  • {BLOCKED}.{BLOCKED}.104.109

The users are redirected to a fake login page such as this fake nonghyup page hosted on {BLOCKED}.{BLOCKED}.245.120:

SOLUTION

Minimum Scan Engine:

9.700

FIRST VSAPI PATTERN FILE:

11.334.02

FIRST VSAPI PATTERN DATE:

09 Dec 2014

VSAPI OPR PATTERN File:

11.335.00

VSAPI OPR PATTERN Date:

09 Oct 2014

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

Scan your computer with your Trend Micro product and note files detected as TSPY_BANKER.YYSI

Step 3

Restart in Safe Mode

[ Learn More ]

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
    • MyKB = "{malware path and filename}"

Step 5

Restore this modified 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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
    • From: ProxyEnable = "1"
      To: ProxyEnable = "{user-defined}"

Step 6

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