oss-security - Re: Problems in automatic crash analysis frameworks

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Message-ID: <1996357174.366899.1429091144055.JavaMail.zimbra@redhat.com>
Date: Wed, 15 Apr 2015 05:45:44 -0400 (EDT)
From: Jakub Filak <jfilak@...hat.com>
To: oss-security@...ts.openwall.com
Subject: Re: Problems in automatic crash analysis frameworks

Hello,

I have a question regarding the ABRT vulnerabilities. I don't particularly understand how an attacker can use /proc/pid/exe symlink to force ABRT to read an arbitrary file if the symlink cannot be changed and kernel refuses to create the process if the symlink's target is not executable.

> This code trusts the /proc/pid/exe symlink, even though it is possible
> to link it anywhere you want.
>
> https://github.com/abrt/abrt/blob/master/src/hooks/abrt-hook-ccpp.c#L368
>
>        sprintf(buf, "/proc/%lu/exe", (long)pid);
>        int src_fd_binary = open(buf, O_RDONLY); /* might fail and
>                                                    return -1, it's ok */

Thank you for clarifying this for me.

Kind regards,
Jakub

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