Full Disclosure mailing list archives
Re: ptrace exploit workaround
From: Jose Carlos Luna Duran <luna () aditel org>
Date: Wed, 19 Mar 2003 08:42:47 +0100
En Tue Mar 18, 2003 at 11:57:25PM +0100, Juraj Bednar <juraj () bednar sk> escribio:
Hi, while waiting for kernel compilations from Debian (and while waiting for my kernel compilations to finish), I coded a single module, which acts as a workaround for one particular exploit I found in one user's homedirectory. Disclaimer: 1.) I don't guarantee, that it will protect you from other exploits (it won't). 2.) I guarantee, it won't break anything (actually it will break some occassional ptrace situations, but for simple gdb and stuff, this is ok). 3.) I don't guarantee it will work. It may freeze your machine. YMMV. 4.) I'm not a linux kernel module coder. If you'll come with something better, drop me a note. 5.) Against this exploit, simple chmod 700 /proc would suffice (since it wants to open /proc/self/exe). This is somehow cleaner.
Hi Juraj, that exploit that you mention about is publicly available on a very well known site (hack.co.za). So, full-disclosure readers may want to take a look at it.
From my point of view protecting the /proc will do nothing, you can
rewrite that exploit without reading proc in a matter of seconds, it reads it only for the sake of obtaining the complete path of the exploit cause its shellcode payload will do a chown & chmod afterwards on it. In the linux-kernel list there was a post on this subject on monday it also displays an alternative patch for 2.4.20 / 21pre: http://www.uwsg.iu.edu/hypermail/linux/kernel/0303.2/0226.html
6.) It should unload correctly, if it won't freeze your system (see point 3:). Anyways, as a simple workaround, it works for me, so I thought I'll post it, it may help you overcome this ugly time. Compilation instruction in source comment. J. -- Juraj Bednar http://www.jurajbednar.com/ http://juraj.bednar.sk/
Best regards, -- Jose Carlos Luna Duran @ UJI luna () aditel org / Jose.Carlos.Luna () cern ch Office Tel. +41 22 76 71880 _______________________________________________ Full-Disclosure - We believe in it. Charter: http://lists.netsys.com/full-disclosure-charter.html
Current thread:
- ptrace exploit workaround Juraj Bednar (Mar 18)
- Re: ptrace exploit workaround Juraj Bednar (Mar 18)
- Re: ptrace exploit workaround Jose Carlos Luna Duran (Mar 18)