F-Secure Trojan Information Pages : Ginwui.A [ Summary ] | [ Detailed Description ] | [ Detection ] Name: Ginwui.A Alias: W32/Ginwui.A, W32/Ginwui.A.dr, Backdoor.Ginwui Type: Backdoor Category: Trojan Platform: Win32 Summary Ginwui is a fully featured backdoor with rootkit characteristics. This backdoor is distributed inside a Word document file with shell-code that drops the backdoor's file to the hard drive and activates it. Detailed Description The shell-code in the Word document decrypts and drops the backdoor's file as CSRSE.EXE to the system's temporary folder and activates it. After being run, the dropped file in its turn extracts and drops another file to the system. This file is dropped as WINGUIS.DLL to Windows System folder and its DoHook function is activated by the dropper. The dropper then deletes itself from the system. The dropped DLL file is the main backdoor component. It traps several functions and modifies information that is passed to the user. As a result, the backdoor's file, startup key in the Registry, and process are not visible to the user. The backdoor creates a startup key for its file in the Registry: [HKLM\Software\Microsoft\Windows NT\CurrentVersion\Windows] "AppInit_DLLs" = "%WinSysDir%\winguis.dll" - where %WinSysDir% represents the Windows System folder that by default has the name C:\Windows\System32\. When active, the backdoor connects to a specified address in order to receive commands from a hacker. The backdoor allows the hacker to do any of the following on an infected computer: Create, read, write, delete and search for files and directories Access and modify the Registry Manipulate services Start and kill processes Take screenshots Enumerate open windows Create its own application window Get information about infected computer Lock, restart or shutdown Windows Create a pipe and read files from it Start a remote command shell Enumerate network resources The backdoor also creates three empty SYS files in the \drivers\ subfolder of Windows System folder. Back to the Top Detection F-Secure Anti-Virus detects this malware with the following updates: [FSAV_Database_Version] Version = 2006-05-19_03. Back to the Top Write-up: Alexey Podrezov, May 19, 2006 Technical Details: Alexey Podrezov, May 19, 2006 F-Secure Corporation