I browse my apache logs every couple of days and I have been finding some entries that I do not know what it is. If you know could you please enlighten me?

[20/Aug/2003:13:25:49 -0700] "GET /scripts/..%255c%255c../winnt/system32/cmd.exe?/c+dir" 404 -

[20/Aug/2003:20:52:25 -0700] "GET /scripts/nsiislog.dll" 404 -

[21/Aug/2003:00:07:51 -0700] "GET /scripts/nsiislog.dll" 404 -

[21/Aug/2003:00:25:56 -0700] "GET /scripts/root.exe?/c+dir HTTP/1.0" 404 276

[21/Aug/2003:00:25:57 -0700] "GET /MSADC/root.exe?/c+dir HTTP/1.0" 404 274

[21/Aug/2003:00:25:57 -0700] "GET /c/winnt/system32/cmd.exe?/c+dir HTTP/1.0" 404 284

[21/Aug/2003:00:25:57 -0700] "GET /d/winnt/system32/cmd.exe?/c+dir HTTP/1.0" 404 284

Is this the way some browsers work, or is this someone or something (worm) trying to mess with the system?

It looks like your server is being hit by a virus designed to crack IIS (microsofts web server). It will have no affect on your system except for preformance if you are getting lots of these hits. If it is mainly one IP then I would inform the owner and possibly put a block on that IP using iptables or hosts.deny

Thank You for the quick reply. After reading the post, I went through and examined a little closer. I do have like 30+ of these by about 20 different IP's. One I did not list looks like they were trying a buffer overflow type thing. I have a few IP's where several came from, so I think I will write to these and let them know. This is my first time doing this type of thing, so I do have one question. Should I include the entry from the log file showing what I am refering to?

Yes I would, but I wouldn't offer your IP address/hostname in the first instance incase it is being done maliciously and this worsens the problem. IT is possible that the people that look after those machines are none the wiser and that the virus is resident in their system.

I used to have a FreeBSD server co-located at a place that was known to be entirely Windows 2k based. He got cracked all the time until he switched over at my urging; however, I recieved the same sort of log entries as you are. Basically it's "script kiddies" trying to find a vulnerable system on a network with software designed to exploit Windows. You need to start worrying only when it stops making reference to a Windows-ish directory structure and DLLs. Still, for your benefit, lock down your system as much as possible (shut down unneeded services, disable telnet, etc.)