TROJ_EXPLOYT.YZS
Exploit.CVE-2012-0158.Gen (BitDefender); Trojan.Mdropper (Norton)
Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)
Threat Type: Trojan
Destructiveness: No
Encrypted: Yes
In the wild: Yes
OVERVIEW
Dropped by other malware
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 executes the dropped file(s). As a result, malicious routines of the dropped files are exhibited on the affected system.
TECHNICAL DETAILS
79,829 bytes
DOC, DOCX
No
25 Aug 2014
Drops files
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 and executes the following files:
- %User Temp%\{malware name and extension} - nonmalicious .RTF file
(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.)
Other System Modifications
This Trojan modifies the following file(s):
- {malware path and file name} - modifies itself into a normal file
It deletes the following registry keys:
HKEY_CURRENT_USER\Software\Microsoft\
Office\{office version}\Word\
Resiliency\StartupItems
Dropping Routine
This Trojan drops the following files:
- %User Temp%\word.exe - detected as BKDR_PROXY.YZS
(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.)
It takes advantage of the following software vulnerabilities to drop malicious files:
It executes the dropped file(s). As a result, malicious routines of the dropped files are exhibited on the affected system.
Other Details
More information on this vulnerability can be found below:
SOLUTION
9.700
11.108.02
25 Aug 2014
11.109.00
25 Aug 2014
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
Remove malware/grayware files dropped/downloaded by TROJ_EXPLOYT.YZS. (Note: Please skip this step if the threats listed below have already been removed.)
- BKDR_PROXY.YZS
Step 4
Search and delete this file
- %User Temp%\{malware name and extension}
- %User Temp%\word.exe
Step 5
Scan your computer with your Trend Micro product to delete files detected as TROJ_EXPLOYT.YZS. 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 deleted registry key/value from backup
*Note: Only Microsoft-related keys/values will be restored. If the malware/grayware also deleted registry keys/values related to programs that are not from Microsoft, please reinstall those programs on your computer.
- In HKEY_CURRENT_USER\Software\Microsoft\ Office\{office version}\Word\Resiliency
- StartupItems
- StartupItems
Step 7
Download and apply these security patches 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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