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BKDR_KELIHOS.YVB

August 07, 2015
 ALIASES:

Trojan.Win32.Generic!BT (Sunbelt); Trojan horse Atros.BPUL (AVG)

 PLATFORM:

Windows

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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.

  TECHNICAL DETAILS

File Size:

1,058,888 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

09 Jul 2015

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 creates the following folders:

  • %User Profile%\CryptnetUrlCache\MetaData
  • %User Profile%\Microsoft\CryptnetUrlCache
  • %User Profile%\CryptnetUrlCache\Content
  • %User Profile%\Application Data\dyGoXwP
  • %User Profile%\Application Data\aMLBWPG

(Note: %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.)

Dropping Routine

This backdoor drops the following files:

  • %User Profile%\MetaData\696F3DE637E6DE85B458996D49D759AD
  • %User Profile%\Content\696F3DE637E6DE85B458996D49D759AD
  • %User Profile%\MetaData\7396C420A8E1BC1DA97F1AF0D10BAD21
  • %User Profile%\Content\7396C420A8E1BC1DA97F1AF0D10BAD21
  • %User Profile%\dyGoXwP\4016900e408043debe45667d85d15ea1
  • %User Profile%\dyGoXwP\345051d18feb43dbac5cb77c5585510e
  • %User Profile%\aMLBWPG\RrVdiA.exe
  • %User Startup%\aMLBWPG.url
  • %User Profile%\dyGoXwP\8c14d075caea4efaa07e835dafff7844
  • %User Profile%\dyGoXwP\f117f21718a8437ea3f3caa870efbdee
  • %User Profile%\dyGoXwP\e928459beb724801a3279475d4905880
  • %User Profile%\dyGoXwP\663fbb6373fd4f60a8a07f6c9ba9f228
  • %User Profile%\dyGoXwP\c05d48f0c68346f3b17018d945381e5f
  • %User Temp%\tmpF.tmp
  • %User Temp%\tmp13.tmp
  • %User Temp%\tmp17.tmp

(Note: %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.. %User Startup% is the current user's Startup folder, which is usually C:\Documents and Settings\{user}\Start Menu\Programs\Startup on Windows 2000 and XP, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup on Windows Vista, 7, and 8.. %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 backdoor connects to the following possibly malicious URL:

  • {BLOCKED}5.24.171
  • {BLOCKED}8.141.75
  • {BLOCKED}.62.201
  • {BLOCKED}6.112.172
  • {BLOCKED}.248.178
  • {BLOCKED}.22.108

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

Search and delete these components

[ Learn More ]
There may be some components 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 Profile%\MetaData\696F3DE637E6DE85B458996D49D759AD
  • %User Profile%\Content\696F3DE637E6DE85B458996D49D759AD
  • %User Profile%\MetaData\7396C420A8E1BC1DA97F1AF0D10BAD21
  • %User Profile%\Content\7396C420A8E1BC1DA97F1AF0D10BAD21
  • %User Profile%\dyGoXwP\4016900e408043debe45667d85d15ea1
  • %User Profile%\dyGoXwP\345051d18feb43dbac5cb77c5585510e
  • %User Profile%\aMLBWPG\RrVdiA.exe
  • %User Startup%\aMLBWPG.url
  • %User Profile%\dyGoXwP\8c14d075caea4efaa07e835dafff7844
  • %User Profile%\dyGoXwP\f117f21718a8437ea3f3caa870efbdee
  • %User Profile%\dyGoXwP\e928459beb724801a3279475d4905880
  • %User Profile%\dyGoXwP\663fbb6373fd4f60a8a07f6c9ba9f228
  • %User Profile%\dyGoXwP\c05d48f0c68346f3b17018d945381e5f
  • %User Temp%\tmpF.tmp
  • %User Temp%\tmp13.tmp
  • %User Temp%\tmp17.tmp

Step 3

Search and delete these folders

[ 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 Profile%\CryptnetUrlCache\MetaData
  • %User Profile%\Microsoft\CryptnetUrlCache
  • %User Profile%\CryptnetUrlCache\Content
  • %User Profile%\Application Data\dyGoXwP
  • %User Profile%\Application Data\aMLBWPG

Step 4

Scan your computer with your Trend Micro product to delete files detected as BKDR_KELIHOS.YVB. 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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