RE: bash_history

["Alexandre Skyrme" <alexandre.skyrme () ciphersec com br>]

Greetings,

        Altering permissions on files that are inside a user's home
directory usually is not an appropriate solution to prevent the user from
erasing his shell history. Tipically the user will have write permission on
the directory itself (since it's his own home) and thus it'll be able to
erase the file (even if the file is owned by root:root and has no write
permission).

        Altering the behavior of commands would probably be bad from a
functionality point of view.

        The best (but probably not perfect) solution would be to define all
history related variables as readonly (like others stated) and use chattr to
protect the history file itself. One must rebember though that are other
variables than just HISTSIZE and HISTFILE (HISTCONTROL, HISTFILESIZE,
HISTIGNORE, etc).

        Still there would probably be ways to bypass that (for example if
the user can change its own shell).

Regards,
--
Alexandre Skyrme
Cipher - Segurança da Informação
+55-21-2542-6677
www.ciphersec.com.br

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> -----Original Message-----
> From: Alejandro Flores [mailto:alejandro.flores () triforsec com br] 
> Sent: sexta-feira, 8 de abril de 2005 18:51
> To: security-basics () securityfocus com
> Subject: bash_history
>
>
> Hey there,
>
> I was googling about a way to protect the bash_history file 
> from user removal or UNSET the HISTFILE variable and all I 
> found was papers about disabling this file for security 
> reasons. Weird! Why it's recommended to disable this file, 
> when it contains the history of typed commands from all 
> users? Ok, ok, you can tell me that users may have typed 
> passwords in a bash session to gain access to a mysql 
> database for example. 
> But, if you need to do some forensics in your compromised 
> server, this file is the first place to know what the 
> 'malicious dude' did to gain root privileges, the server 
> where he downloaded his craps, etc... I started 'chown'ing 
> the .bash_profile and .bashrc files to root, and removed the 
> 'wx' from group and others. The user has only read 
> permission. But I can't prevent him from changing the 
> HISTFILE variable. Like: export HISTFILE=/dev/null With this 
> command, all my steps from now aren't recorded.
>
> Ideas?
>
> Regards,
> Alejandro Flores
>
>
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Earn your MS in Information Security ONLINE
Organizations worldwide are in need of highly qualified information security
professionals.  Norwich University is fulfilling this demand with its MS in
Information Security offered online.  Recognized by the NSA as an
academically excellent program, NU offers you the opportunity to earn your
degree without disrupting your home or work life.

http://www.msia.norwich.edu/secfocus_en
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