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TSPY_IISNIFF.NIL

December 18, 2013
 Analysis by: Mark Joseph Manahan
 ALIASES:

TrojanDropper:Win32/Vorsii.A (Microsoft), Infostealer.Isniffer (Symantec), Win32/Spy.IISniff.A trojan (Eset)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

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

  • Threat Type: Spyware

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Dropped by other malware, Downloaded from the Internet

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 executes commands from a remote malicious user, effectively compromising the affected system.

It monitors user transactions on certain sites.

  TECHNICAL DETAILS

File Size:

697,344 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

12 Dec 2013

Payload:

Compromises system security, 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.

Installation

This spyware drops the following component file(s):

  • {Malware Path}\{Malware Name}.dll - also detected as TSPY_IISNIFF.NIL
  • {Malware Path}\{Malware Name}.vbs - detected as VBS_IISN.NIL - used to install/remove component as IIS Module

Backdoor Routine

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

  • isn_getlog -> return log contents
  • isn_logdel -> delete log files
  • isn_logpath -> return log path

Dropping Routine

This spyware drops the following files:

  • {Malware Path}\{Malware Name}.cfg - URIs to monitor specified through running parameter '-i' during installation of malware
  • {Malware Path}\{Malware Name and Extension}.log - contains system information,location of config and component, errors and collected network dumps from monitored sites

Information Theft

This spyware monitors user transactions done on the following websites:

  • Sites with strings specified in {Malware Path}\{Malware Name}.cfg

It accepts the following parameters:

  • -path -> if this is specified, {Malware Path} is replaced by specified path
  • -i -> strings to monitor (configuration)
  • -u -> uninstall itself
  • -is632 -> indicate that machine is 32bit
  • -is664 -> indicate that machine is 64bit

  SOLUTION

Minimum Scan Engine:

9.700

FIRST VSAPI PATTERN FILE:

10.468.06

FIRST VSAPI PATTERN DATE:

12 Dec 2013

VSAPI OPR PATTERN File:

10.469.00

VSAPI OPR PATTERN Date:

12 Dec 2013

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

Remove malware/grayware files dropped/downloaded by TSPY_IISNIFF.NIL

    • VBS_IISN.NIL

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

Search and delete these files

[ 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.  
  • {Malware Path}\{Malware Name}.dll
  • {Malware Path}\{Malware Name}.vbs
  • {Malware Path}\{Malware Name}.cfg
  • {Malware Path}\{Malware Name and Extension}.log

Step 5

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