PE_QUERVAR.F-O

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

Arrival Details

This file infector 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 file infector drops the following copies of itself into the affected system:

• %User Profile%\Application Data\{random folder name}\{random file name}.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 drops the following component file(s):

• %User Profile%\Application Data\{random folder name}\{random file name}.exe.lnk
• %User Profile%\Application Data\{random folder name}\{random file name}.exe.ini

(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\{random folder name}

(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 file infector modifies the following registry entries to ensure it automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Windows
load = "%User Profile%\Application Data\{random folder name}\{random filename}.exe.lnk"

(Note: The default value data of the said registry entry is "".)

File Infection

This file infector infects the following file types:

• exe
• doc
• docx
• xls
• xlsx

NOTES:

It renames the extension of the infected file as follows:

• .doc to .cod.scr
• .docx to .xcod.scr
• .xls to .slx.scr
• .xlsxto .xslx.scr

It then deletes the original copy of the infected files.