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On Thursday 14 August 2003 06:47, Mathieu Jobin wrote:
> If there is a backdoor/rootkit install, maybe someone modify your login
> program and now get your rootpasswd somewhere else. Maybe hardcoded in your
> login program.

more than maybe: almost definitely. /bin/login trojans are probably one of the 
most common bits of payload in rootkits. humourously, the script kiddies 
often screw up and even manage to do things that render a machine unable to 
log a user in... i remember one login trojan that had an error where the 
first time you'd type in the username it would just ignore it and ask for 
your username again (no password prompt in between). this was, of course, a 
dead giveaway...

> I dont remember the exact option, since i didnt use RPM last few years, but
> I remember using such a command that tell if a file differ from the one
> that comes with the package.

`rpm --verify` or just `rpm -V`, as Jesse already noted...

> that help finding rootkit/backdoor

not necessarily. what if the rootkit is a clever one and it changes your rpm 
database to think the trojanned files are the originals? or if it installs a 
trojan libc that mis-reports stat calls made on the rootkit payload? or a 
kernel mod? 

and of course, this only helps with rootkits that disturb files that were 
previously installed.... of course, most rootkits aren't so clever ...

but once the machine is compromised, the game is over and nothing can really 
be trusted. it's time to pack up, reformat, and try again. =/

- --
Aaron J. Seigo
GPG Fingerprint: 8B8B 2209 0C6F 7C47 B1EA  EE75 D6B7 2EB1 A7F1 DB43
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