ALIASES:

TrojanDownloader:Win32/Recslurp.A (Microsoft); RDN/Generic PWS.y!wl (McAfee); Trojan.Smoaler (Symantec); Trojan-PSW.Win32.Tepfer.ssuo (Kaspersky); Mal/Inject-EQ (Sophos); Trojan.Win32.Generic!BT (Sunbelt); Win32/Cryptor (AVG)

 PLATFORM:

Windows

 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.

It deletes itself after execution.

  TECHNICAL DETAILS

File Size: 153,600 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 04 Oct 2014

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 drops the following copies of itself into the affected system:

  • %User Profile%\Application Data\csrss.exe
  • %User Profile%\System32\rundll32.exe
  • %User Profile%\Application Data\svchost.exe

(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.)

It creates the following folders:

  • %User Profile%\Application Data\System32

(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.)

Autostart Technique

This Trojan adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Client Server Runtime Process = "%User Profile%\Application Data\csrss.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
Client Server Runtime Process = "%User Profile%\Application Data\csrss.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Host-process Windows (Rundll32.exe) = "%User Profile%\System32\rundll32.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
Host-process Windows (Rundll32.exe) = "%User Profile%\System32\rundll32.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Service Host Process for Windows = "%User Profile%\Application Data\svchost.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
Service Host Process for Windows = "%User Profile%\Application Data\svchost.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Host-process Windows (Rundll32.exe) = "%User Profile%\Application Data\csrss.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
Host-process Windows (Rundll32.exe) = "%User Profile%\Application Data\csrss.exe"

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CURRENT_USER\SOFTWARE\BC Clients

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
Client Server Runtime Process = "%User Profile%\Application Data\csrss.exe"

HKEY_CURRENT_USER\Software\BC Clients
0 = ".{RM#'$H/::l -R+=8(.^]Y #7;Y]O9-;*L5'&aV(Y R*?3!:ƒ$6,"

HKEY_CURRENT_USER\Software\BC Clients
f = "œ"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
Host-process Windows (Rundll32.exe) = "%User Profile%\System32\rundll32.exe"

HKEY_CURRENT_USER\Software\BC Clients
1 = ".{RM#'$H/::l -R+=8(.^]Y #7;Y]O9-;*L5'&aV(Y RZ52&,@rU4-A-}{b$*,"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
Service Host Process for Windows = "%User Profile%\Application Data\svchost.exe"

HKEY_CURRENT_USER\Software\BC Clients
2 = ".{RM#'$H/::l -R+=8(.^]Y #7;Y]O9-;*L5'&aV(Y R:::&^5`,4$"

HKEY_CURRENT_USER\Software\BC Clients
d = "N{RxB`q/uyJIvgp.wLKyygJ•G{rWp/t~Myvgp”px"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
Host-process Windows (Rundll32.exe) = "%User Profile%\Application Data\csrss.exe"

HKEY_CURRENT_USER\Software\BC Clients
f = "Ÿ"

HKEY_CURRENT_USER\Software\BC Clients
s = "œqwg~rdg•u`xui9D-'?o,Y"

Other Details

This Trojan connects to the following possibly malicious URL:

  • {BLOCKED}176.126
  • {BLOCKED}6.84.104
  • {BLOCKED}3.19
  • {BLOCKED}37.104
  • {BLOCKED}33.135
  • {BLOCKED}.112.35
  • {BLOCKED}.8.167
  • {BLOCKED}.217.203
  • {BLOCKED}.112.33
  • {BLOCKED}37.88
  • {BLOCKED}.112.32
  • {BLOCKED}.217.202
  • {BLOCKED}37.120
  • {BLOCKED}.47.114

It deletes itself after execution.

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine: 9.700

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_CURRENT_USER\SOFTWARE
    • BC Clients

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • Client Server Runtime Process = "%User Profile%\Application Data\csrss.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • Client Server Runtime Process = "%User Profile%\Application Data\csrss.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • Host-process Windows (Rundll32.exe) = "%User Profile%\System32\rundll32.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • Host-process Windows (Rundll32.exe) = "%User Profile%\System32\rundll32.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • Service Host Process for Windows = "%User Profile%\Application Data\svchost.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • Service Host Process for Windows = "%User Profile%\Application Data\svchost.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • Host-process Windows (Rundll32.exe) = "%User Profile%\Application Data\csrss.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • Host-process Windows (Rundll32.exe) = "%User Profile%\Application Data\csrss.exe"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
    • Client Server Runtime Process = "%User Profile%\Application Data\csrss.exe"
  • In HKEY_CURRENT_USER\Software\BC Clients
    • 0 = ".{RM#'$H/::l -R+=8(.^]Y #7;Y]O9-;*L5'&aV(Y R*?3!:ƒ$6,"
  • In HKEY_CURRENT_USER\Software\BC Clients
    • f = "œ"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
    • Host-process Windows (Rundll32.exe) = "%User Profile%\System32\rundll32.exe"
  • In HKEY_CURRENT_USER\Software\BC Clients
    • 1 = ".{RM#'$H/::l -R+=8(.^]Y #7;Y]O9-;*L5'&aV(Y RZ52&,@rU4-A-}{b$*,"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
    • Service Host Process for Windows = "%User Profile%\Application Data\svchost.exe"
  • In HKEY_CURRENT_USER\Software\BC Clients
    • 2 = ".{RM#'$H/::l -R+=8(.^]Y #7;Y]O9-;*L5'&aV(Y R:::&^5`,4$"
  • In HKEY_CURRENT_USER\Software\BC Clients
    • d = "N{RxB`q/uyJIvgp.wLKyygJ•G{rWp/t~Myvgp”px"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
    • Host-process Windows (Rundll32.exe) = "%User Profile%\Application Data\csrss.exe"
  • In HKEY_CURRENT_USER\Software\BC Clients
    • f = "Ÿ"
  • In HKEY_CURRENT_USER\Software\BC Clients
    • s = "œqwg~rdg•u`xui9D-'?o,Y"

Step 5

Search and delete this folder

[ 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%\Application Data\System32

Step 6

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