Analysis by: Sammy Chua
ALIASES:

Worm.Win32.Cridex.qtl (Kaspersky); Trojan.Cridex (Symantec); Troj/Dridex-FQ (Sophos); W32/Cridex.P!worm (Fortinet); Backdoor:Win32/Drixed.D (Microsoft);

 PLATFORM:

Windows

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

  • Threat Type: Spyware

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel: Downloaded from the Internet, Dropped by other malware

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 may be downloaded from remote sites by other malware.

It connects to certain websites to send and receive information. However, as of this writing, the said sites are inaccessible. It deletes itself after execution.

  TECHNICAL DETAILS

File Size: 214,368 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 23 Jul 2015
Payload: Connects to URLs/IPs

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.

It may be downloaded from remote site(s) by the following malware:

  • W2KM_DRIDEX.B

Information Theft

This spyware gathers the following data:

  • Username
  • Computer Name
  • Installation Date
  • Operating System version
  • Installed Programs and version

Other Details

This spyware connects to the following website to send and receive information:

  • {BLOCKED}.{BLOCKED}.199.246:543
  • {BLOCKED}.{BLOCKED}.96.45:4543
  • {BLOCKED}.{BLOCKED}.251.33:743
  • {BLOCKED}.{BLOCKED}.214.106:448
  • {BLOCKED}.{BLOCKED}.123.100:743

However, as of this writing, the said sites are inaccessible.

It deletes itself after execution.

NOTES:

If User Account Control (UAC) is enabled in the affected system, it does the following:

  • Drops a copy of itself as %AppDataLocal%\{random folder name}\{random file name}.exe
  • Drops the file %AppDataLocal%\{random 8 characters} that is deleted afterwards

For the malware to execute with administrative privileges, it injects its code to explorer.exe to load sysprep.exe and cryptbase.dll to allow the malware to run without the UAC notification warnings.

  SOLUTION

Minimum Scan Engine: 9.750
FIRST VSAPI PATTERN FILE: 11.808.05
FIRST VSAPI PATTERN DATE: 09 Jul 2015
VSAPI OPR PATTERN File: 11.781.00
VSAPI OPR PATTERN Date: 10 Jul 2015

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

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

Remove the malware/grayware file that dropped/downloaded TSPY_DRIDEX.XYU. (Note: Please skip this step if the threat(s) listed below have already been removed.)

    • W2KM_DRIDEX.B

Step 5

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.
  • %AppDataLocal%\{random 8 characters}

Step 6

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