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Date: Thu, 04 Dec 2014 11:26:17 +0100
From: Martino Dell'Ambrogio <tillo@...lo.ch>
To: oss-security@...ts.openwall.com
Subject: Re: CVE request: procmail heap overflow in getlline()
For what is worth, I strongly believe this is a security bug for the
same reason.
As soon as there is an undocumented way to execute code, it will be
impossible for a .procmailrc file generator to avoid execution of code.
Workaround measures like security capabilities can not be taken into
account as they are not implicit.
Martino Dell'Ambrogio
Security Auditor
Web: http://www.tillo.ch/
Email: tillo@...lo.ch
On 12/04/2014 10:58 AM, Florian Weimer wrote:
> On 12/04/2014 09:41 AM, Kurt Seifried wrote:
>> On 04/12/14 12:57 AM, Santiago Vila wrote:
>>> On Wed, Dec 03, 2014 at 05:30:57PM -0600, Joshua J. Drake wrote:
>>>> Is it possible to trigger this issue with untrusted input or only
>>>> trusted input from procmailrc?
>>>
>>> This is an issue with the handling of .procmailrc file, which contains
>>> the filter rules for procmail. An external attacker is not supposed to
>>> provide the .procmailrc file at /home/user, only the email to be
>>> filtered, so, IMHO, this is a bug but maybe not a security bug.
>>>
>>> Thanks.
>>
>> I disagree. Many mail servers allow people to edit their .procmailrc but
>> explicitly block shell accounts. This would allow a user with a non
>> interactive shell account to execute arbitrary commands using procmailrc
>> even if they were otherwise restricted (e.g. using permissions or
>> SELinux for example).
>
> procmail already executes commands in lines starting with “|” (and the
> documentation suggests it does not honor SHELL, so SHELL=/bin/false
> does not block this). If permissions/SELinux contain that, they will
> also work against a procmailrc parser exploit. In other words, I
> don't think there's a security bug here.
>
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