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Message-ID: <CAJ_zFk+JM3PVN=WkyFokdHP2=s87NFaYn89Fy=WSxEgYC3CE6g@mail.gmail.com>
Date: Wed, 15 Apr 2015 13:44:45 -0700
From: Tavis Ormandy <taviso@...gle.com>
To: oss-security@...ts.openwall.com
Subject: Re: Re: Problems in automatic crash analysis frameworks
On Wed, Apr 15, 2015 at 2:45 AM, Jakub Filak <jfilak@...hat.com> wrote:
> 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.
>
My description was incorrect, It can't be an arbitrary file, just a
file you have execute but not read permission.
Tavis.
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