Name :	Piggi.A
Size:	73,216
Category:	Malware
Type:	Email-Worm
Platform:	W32
Date of Discovery:	January 02, 2007

Piggi.A mass mails itself and collects e-mail addresses. Piggi.A kills processes belonging to anti-virus and security software and has a rootkit functionality.

Automatic Disinfection

Usually standalone malware (backdoors, worms, trojans, etc.) is automatically removed by F-Secure Anti-Virus (FSAV) starting from version 5.40. Malware files get automatically renamed by FSAV, so they can not be started any more. In some rare cases, when automatic disinfection is not possible, a user can select disinfection action by him/herself to make FSAV rename or delete an infected file. In some special cases, it is recommended to use specific disinfection tools provided by F-Secure. They can be downloaded from our ftp site:

ftp://ftp.f-secure.com/anti-virus/tools/

F-Secure Anti-Virus can be purchased from our webshop or from our authorized distributors. A trial version F-Secure Anti-Virus, limited to 30 days, can be downloaded from our website:

http://www.f-secure.com/download-purchase/

All the latest versions of FSAV can download anti-virus database updates automatically. However, these updates can be also downloaded and installed manually from our web or ftp sites:

http://www.f-secure.com/download-purchase/updates.shtml


Manual Disinfection

To manually disinfect standalone malware (backdoors, worms, trojans, etc.) it's usually enough to delete all infected files from a computer and to restart it. Active malware files are usually locked by operating system so different disinfection approaches are required for different operating systems.
Please note that manual disinfection is a risky process, so it is recommended only for advanced users.

If Windows 95, 98 and ME operating system are used, it is recommended to restart a computer from a bootable system diskette and to delete an infected file from the command prompt. For example, if a malicious file named ABC.EXE is located in the Windows folder, it is usually enough to type the following command at the command prompt:

DEL C:\WINDOWS\ABC.EXE

and press Enter. After that, the infected file will be gone. If Windows NT, 2000 or XP are used, a malicious file has to be renamed with a different extension (for example .VIR) and then the system has to be restarted. After restarting, a renamed malicious file will no longer be active and it can be easily to delete manually.


Malware Disinfection Tools

F-Secure provides disinfection tools for certain malware. These tools can be downloaded from this webpage:

http://www.f-secure.com/download-purchase/tools.shtml

ftp://ftp.f-secure.com/anti-virus/tools/


Windows System Restore Issues

If Windows ME or XP are used, it is recommended to disable System Restore features of these operating systems to prevent a computer from re-infection by an already removed malware. The fact is that System Restore features of these operating systems might save an infected file into the special folder and copy it back to a hard drive every time it has been renamed or deleted by F-Secure Anti-Virus or by a user. Instructions on how to disable the System Restore features are here:

Windows ME:
http://www.f-secure.com/v-descs/sfc_dis.shtml

Windows XP:
http://www.f-secure.com/v-descs/sfc_dis1.shtml

It is recommended to re-enable System Restore features after disinfection in order to restore stable system configuration in the future, if any crash or incompatibility issue occurs.


Failed Disinfection

In some cases, F-Secure Anti-Virus might not disinfect a system automatically. In this case, please visit our Support pages at:

http://support.f-secure.com/enu/home/virusproblem/howtoclean/

System Infection
Upon execution, Piggi.A creates the following registry entries so as to start automatically with Windows:


It also drops a file named msfsr.sys in the Windows system directory and another random .sys file on C:\WINDOWS\system32\drivers\ and starts them as a service.

These are the registry keys for the services Piggi.A creates:


It will also copy itself to "C:\Program Files\Internet Explorer\iexplore.exe". The original iexplore.exe will be moved to the folder:


It also creates copies of itself to folders with the following strings:


The filename is any of the following:


The file name includes any of the following extensions:


Examples:



Stops Antivirus Services
Piggi.A also stops running antivirus services with the following names:


Then copies itself to the following folders:


This is to ensure that these antivirus applications cannot perform an automatic update.


Rootkit Capability
This malware hides its own process and files using two kernel-mode drivers.

These are:

msfsr.sys - dropped in the Windows system directory and run as service. This creates a device, so that user-mode can communicate with it and allows the user-mode component to hide any process_id it wants.

[random_name].sys - dropped in %windir%\system32\drivers\ and run as service. This hides any files that are defined in the created c:\zyxwvuts.log file. Below is an example of the string inside the said file:



Spreading via E-mail
The worm collects e-mail addresses from the infected computer. It locates the WAB (Windows Address Book) file and Temporary Internet files. The following are the details:

The worm sends itself as attachment to the gathered e-mail addresses using the following format:

TO:


FROM:
The From field may use any of these addresses:


They may use any of these domain names:


SUBJECT:


ATTACHMENT:
The filenames of the attachment may contain any of these strings:


With any of the following extensions:


Example:


BODY:
This malware uses a pool of strings to search and combine to create the body of the e-mail. The following are some of the strings that can be found in the e-mail's body:



Below are examples of the the possible string combinations that can be found in the body of the email:




Other
Piggi.A also continues queries to the site mi5.gov.uk.

This malware comes packed with Yoda Protector 1.03.3