ALIASES:

Backdoor:Win32/Cycbot.G (Microsoft); BackDoor-EXI.gen.k (McAfee); Backdoor.Cycbot!gen4 (Symantec); Backdoor.Win32.Cycbot.b (v) (Sunbelt); Gen:Heur.Conjar.9 (FSecure)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This Trojan 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: 209,920 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 20 Jul 2012

Arrival Details

This Trojan 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 Trojan creates the following folders:

  • %User Profile%\CryptnetUrlCache\MetaData
  • %User Profile%\Microsoft\CryptnetUrlCache
  • %User Profile%\CryptnetUrlCache\Content

(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.)

Other System Modifications

This Trojan deletes the following folders:

  • %User Profile%\My Documents\My Pictures
  • %Start Menu%\Programs\Administrative Tools

(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.. %Start Menu% is the current user's Start Menu folder, which is usually C:\Windows\Start Menu or C:\Documents and Settings\{User name}\Start Menu on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming\Microsoft\Windows\Start Menu on Windows Vista and 7.)

It adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
SystemCertificates\TrustedPublisher

HKEY_CURRENT_USER\Software\Microsoft\
SystemCertificates\TrustedPublisher\Certificates

HKEY_CURRENT_USER\Software\Microsoft\
SystemCertificates\TrustedPublisher\CRLs

HKEY_CURRENT_USER\Software\Microsoft\
SystemCertificates\TrustedPublisher\CTLs

HKEY_CURRENT_USER\Software\Policies\
Microsoft\SystemCertificates\TrustedPublisher

HKEY_CURRENT_USER\Software\Policies\
Microsoft\SystemCertificates\TrustedPublisher\
Certificates

HKEY_CURRENT_USER\Software\Policies\
Microsoft\SystemCertificates\TrustedPublisher\
CRLs

HKEY_CURRENT_USER\Software\Policies\
Microsoft\SystemCertificates\TrustedPublisher\
CTLs

It modifies the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Windows
Load = "%User Temp%\csrss.exe"

Dropping Routine

This Trojan drops the following files:

  • %User Temp%\csrss.exe
  • %User Profile%\MetaData\2BF68F4714092295550497DD56F57004
  • %User Profile%\Content\2BF68F4714092295550497DD56F57004
  • %User Profile%\MetaData\94308059B57B3142E455B38A6EB92015
  • %User Profile%\Content\94308059B57B3142E455B38A6EB92015
  • %User Profile%\MetaData\60E31627FDA0A46932B0E5948949F2A5
  • %User Profile%\Content\60E31627FDA0A46932B0E5948949F2A5
  • %User Profile%\MetaData\0797C381B2F87EB5A1D5573BD15BA4F4
  • %User Profile%\Content\0797C381B2F87EB5A1D5573BD15BA4F4
  • %Temp%\e30d.mst
  • %User Profile%\MetaData\7B2238AACCEDC3F1FFE8E7EB5F575EC9
  • %User Profile%\Content\7B2238AACCEDC3F1FFE8E7EB5F575EC9

(Note: %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.. %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.. %Temp% is the Windows Temporary folder, which is usually C:\Windows\Temp.)

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine: 9.200

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

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\SystemCertificates
    • TrustedPublisher
  • In HKEY_CURRENT_USER\Software\Microsoft\SystemCertificates\TrustedPublisher
    • Certificates
  • In HKEY_CURRENT_USER\Software\Microsoft\SystemCertificates\TrustedPublisher
    • CRLs
  • In HKEY_CURRENT_USER\Software\Microsoft\SystemCertificates\TrustedPublisher
    • CTLs
  • In HKEY_CURRENT_USER\Software\Policies\Microsoft\SystemCertificates
    • TrustedPublisher
  • In HKEY_CURRENT_USER\Software\Policies\Microsoft\SystemCertificates\TrustedPublisher
    • Certificates
  • In HKEY_CURRENT_USER\Software\Policies\Microsoft\SystemCertificates\TrustedPublisher
    • CRLs
  • In HKEY_CURRENT_USER\Software\Policies\Microsoft\SystemCertificates\TrustedPublisher
    • CTLs

Step 3

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\Windows NT\CurrentVersion\Windows
    • Load = "%User Temp%\csrss.exe"

Step 4

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 Temp%\csrss.exe
  • %User Profile%\MetaData\2BF68F4714092295550497DD56F57004
  • %User Profile%\Content\2BF68F4714092295550497DD56F57004
  • %User Profile%\MetaData\94308059B57B3142E455B38A6EB92015
  • %User Profile%\Content\94308059B57B3142E455B38A6EB92015
  • %User Profile%\MetaData\60E31627FDA0A46932B0E5948949F2A5
  • %User Profile%\Content\60E31627FDA0A46932B0E5948949F2A5
  • %User Profile%\MetaData\0797C381B2F87EB5A1D5573BD15BA4F4
  • %User Profile%\Content\0797C381B2F87EB5A1D5573BD15BA4F4
  • %Temp%\e30d.mst
  • %User Profile%\MetaData\7B2238AACCEDC3F1FFE8E7EB5F575EC9
  • %User Profile%\Content\7B2238AACCEDC3F1FFE8E7EB5F575EC9

Step 5

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

Step 6

Scan your computer with your Trend Micro product to delete files detected as TROJ_FAKEAV.SMQV. 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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