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BKDR_RASBA.C

May 22, 2013
 ALIASES:

Backdoor:Win32/Agent.GO (Microsoft); W32/RAHack (McAfee); W32.Rahack (Symantec); Worm.Win32.Rahak.a (Kaspersky); BehavesLike.Win32.Malware.ssc (mx-v) (Sunbelt); Trojan horse BackDoor.Agent.5.O (AVG)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 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:

295,684 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

22 May 2013

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 copies of itself into the affected system:

  • %System%\mscolsrv.exe
  • %System%\svchsot.exe
  • %User Temp%\Microsof.exe
  • %Program Files%\Adobe\Reader 10.0\Reader\Legal\ENU\license..exe

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.. %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.. %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), and 7 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), and 7 (64-bit).)

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\Run
sysser = "{malware path and file name}"

Other System Modifications

This backdoor deletes the following files:

  • @A

It adds the following registry keys:

HKEY_CLASSES_ROOT\CLSID\{9DE8CC68-BA1A-D077-ABAB-E2E38CF3B901}

HKEY_CLASSES_ROOT\CLSID\{9DE8CC68-BA1A-D077-ABAB-E2E38CF3B901}\
LocalServer32

HKEY_LOCAL_MACHINE\SOFTWARE\RAdmin\
v1.1\Server\Parameters

HKEY_LOCAL_MACHINE\SYSTEM\RAdmin\
v2.0\Server\Parameters

HKEY_CLASSES_ROOT\CLSID\{3040DD03-9C5A-4563-AC2E-0026188C25A9}

HKEY_CLASSES_ROOT\CLSID\{3040DD03-9C5A-4563-AC2E-0026188C25A9}\
InprocServer32

HKEY_CLASSES_ROOT\CLSID\{3040DD03-9C5A-4563-AC2E-0026188C25A9}\
ProgID

HKEY_CLASSES_ROOT\CLSID\{3040DD03-9C5A-4563-AC2E-0026188C25A9}\
TypeLib

HKEY_CLASSES_ROOT\CLSID\{3040DD03-9C5A-4563-AC2E-0026188C25A9}\
Version

HKEY_CLASSES_ROOT\CLSID\{3040DD03-9C5A-4563-AC2E-0026188C25A9}\
VersionIndependentProgID

HKEY_CLASSES_ROOT\ComDll.1

HKEY_CLASSES_ROOT\ComDll.1\CLSID

HKEY_CLASSES_ROOT\ComDll

HKEY_CLASSES_ROOT\ComDll\CurVer

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{47FC238F-C142-4D8C-A052-DBEEEC4AC7C3}

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{47FC238F-C142-4D8C-A052-DBEEEC4AC7C3}\1.0

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{47FC238F-C142-4D8C-A052-DBEEEC4AC7C3}\1.0\
FLAGS

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{47FC238F-C142-4D8C-A052-DBEEEC4AC7C3}\1.0\
0

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{47FC238F-C142-4D8C-A052-DBEEEC4AC7C3}\1.0\
0\win32

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{47FC238F-C142-4D8C-A052-DBEEEC4AC7C3}\1.0\
HELPDIR

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{7C2DDA92-840E-4C47-A209-A7F51CCA535E}

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{7C2DDA92-840E-4C47-A209-A7F51CCA535E}\ProxyStubClsid

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{7C2DDA92-840E-4C47-A209-A7F51CCA535E}\ProxyStubClsid32

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{7C2DDA92-840E-4C47-A209-A7F51CCA535E}\TypeLib

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{3040DD03-9C5A-4563-AC2E-0026188C25A9}\InprocServer32
ThreadingModel = "both"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{7C2DDA92-840E-4C47-A209-A7F51CCA535E}\TypeLib
Version = "1.0"

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.300

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_CLASSES_ROOT\CLSID
    • {9DE8CC68-BA1A-D077-ABAB-E2E38CF3B901}
  • In HKEY_CLASSES_ROOT\CLSID\{9DE8CC68-BA1A-D077-ABAB-E2E38CF3B901}
    • LocalServer32
  • In HKEY_LOCAL_MACHINE\SOFTWARE\RAdmin\v1.1\Server
    • Parameters
  • In HKEY_LOCAL_MACHINE\SYSTEM\RAdmin\v2.0\Server
    • Parameters
  • In HKEY_CLASSES_ROOT\CLSID
    • {3040DD03-9C5A-4563-AC2E-0026188C25A9}
  • In HKEY_CLASSES_ROOT\CLSID\{3040DD03-9C5A-4563-AC2E-0026188C25A9}
    • InprocServer32
  • In HKEY_CLASSES_ROOT\CLSID\{3040DD03-9C5A-4563-AC2E-0026188C25A9}
    • ProgID
  • In HKEY_CLASSES_ROOT\CLSID\{3040DD03-9C5A-4563-AC2E-0026188C25A9}
    • TypeLib
  • In HKEY_CLASSES_ROOT\CLSID\{3040DD03-9C5A-4563-AC2E-0026188C25A9}
    • Version
  • In HKEY_CLASSES_ROOT\CLSID\{3040DD03-9C5A-4563-AC2E-0026188C25A9}
    • VersionIndependentProgID
  • In HKEY_CLASSES_ROOT
    • ComDll.1
  • In HKEY_CLASSES_ROOT\ComDll.1
    • CLSID
  • In HKEY_CLASSES_ROOT
    • ComDll
  • In HKEY_CLASSES_ROOT\ComDll
    • CurVer
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib
    • {47FC238F-C142-4D8C-A052-DBEEEC4AC7C3}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{47FC238F-C142-4D8C-A052-DBEEEC4AC7C3}
    • 1.0
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{47FC238F-C142-4D8C-A052-DBEEEC4AC7C3}\1.0
    • FLAGS
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{47FC238F-C142-4D8C-A052-DBEEEC4AC7C3}\1.0
    • 0
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{47FC238F-C142-4D8C-A052-DBEEEC4AC7C3}\1.0\0
    • win32
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{47FC238F-C142-4D8C-A052-DBEEEC4AC7C3}\1.0
    • HELPDIR
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface
    • {7C2DDA92-840E-4C47-A209-A7F51CCA535E}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{7C2DDA92-840E-4C47-A209-A7F51CCA535E}
    • ProxyStubClsid
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{7C2DDA92-840E-4C47-A209-A7F51CCA535E}
    • ProxyStubClsid32
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{7C2DDA92-840E-4C47-A209-A7F51CCA535E}
    • TypeLib

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
    • sysser = "{malware path and file name}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{3040DD03-9C5A-4563-AC2E-0026188C25A9}\InprocServer32
    • ThreadingModel = "both"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{7C2DDA92-840E-4C47-A209-A7F51CCA535E}\TypeLib
    • Version = "1.0"

Step 5

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

Step 6

Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.

  • @A


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