This type of worm is embedded in an email attachment, and spreads using the infected computer's emailing networks.
Disinfection of the Luder virus-worm should be performed as follows:
CAUTION Due to the "Email-Worm." detection prefix, F-Secure Anti-Virus will automatically suggest deletion of the infected files. DO NOT select the "Delete" option however, as this worm includes a viral component and the files it infects should be disinfected rather than deleted. At the same time, the worm's dropper and downloader files should be deleted from a computer to prevent its re-infection. See the names of the dropper and downloader files in the Details section.
A False Positive is when a file is incorrectly detected as harmful, usually because its code or behavior resembles known harmful programs. A False Positive will usually be fixed in a subsequent database update without any action needed on your part. If you wish, you may also:
Check for the latest database updates
First check if your F-Secure security program is using the latest detection database updates, then try scanning the file again.
Submit a sample
After checking, if you still believe the file is incorrectly detected, you can submit a sample of it for re-analysis.
NOTE If the file was moved to quarantine, you need to collect the file from quarantine before you can submit it.
Exclude a file from further scanning
If you are certain that the file is safe and want to continue using it, you can exclude it from further scanning by the F-Secure security product.
Note You need administrative rights to change the settings.
Luder is an email worm, a dropper for a trojan downloader and a file infector. The worm sends itself as attachment named 'postcard.exe' (or similar) in email messages with the 'Happy New Year!' subject (or similar). The trojan downloader downloads and runs files from a website.
After the worm's file is run, it copies itself to Windows System folder with the name ppl.exe.The worm also drops a trojan downloader file with a random name into the Windows System folder and starts it.
Before spreading, the worm collects email addresses from an infected computer. It locates and reads the WAB (Windows Address Book) file. The worm sends messages with the following characteristics:
Later variants of the worm use different Subject fields and Attachment names.The worm avoids sending emails to email addresses that contain any of the following:
The worm scans all fixed and remote drives starting from Z: to C: and looks for files with the following extensions:
The worm collects additional email addresses to spread to files with .hta, .txt and .htm extensions.The files with .scr and .exe extensions get infected. For every executable file found, the worm creates a copy with a random name and a .t extension. Then it tries to infect the files, if they are in PE (Portable Executable) format. The worm inserts a small piece of code into the victim files and then redirects the entry point to that address. This small piece of code starts the worm's copy (randomly named file with .t extension) and then passes control to the host file.It should be noted that the worm is quite buggy and can corrupt files upon infection. Files with .rar extension are not affected, but the worm's author probably plans to process them in future versions of his malware. The worm also does not infect files protected by Windows Safe File Check.The worm terminates processes with the following substrings in their names:
In addition the worm closes the Registry Editor's window.
Creates these keys: