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Date: Fri, 24 May 2013 01:17:40 -0600
From: Kurt Seifried <kseifried@...hat.com>
To: oss-security@...ts.openwall.com
CC: Timo Sirainen <tss@....fi>, Jan Lieskovsky <jlieskov@...hat.com>,
        Agostino Sarubbo <ago@...too.org>
Subject: Re: CVE request: dovecot : "APPEND" Parameters Processing
 Denial of Service Vulnerability

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On 05/22/2013 06:24 AM, Timo Sirainen wrote:
> On 22.5.2013, at 15.17, Jan Lieskovsky <jlieskov@...hat.com>
> wrote:
> 
>> ----- Original Message -----
>>> From: "Agostino Sarubbo" <ago@...too.org> To:
>>> oss-security@...ts.openwall.com Sent: Tuesday, May 21, 2013
>>> 8:58:04 PM Subject: [oss-security] CVE request: dovecot :
>>> "APPEND" Parameters Processing Denial of Service Vulnerability
>>> 
>>> From the secunia advisory SA53492[1] :
>>> 
>>> Description A vulnerability has been reported in Dovecot, which
>>> can be exploited by malicious users to cause a DoS (Denial of
>>> Service).
>>> 
>>> The vulnerability is caused due to an error within IMAP
>>> functionality when processing the "APPEND" parameters and can
>>> be exploited to cause a hang.
>> 
>> Timo, in relation with the previous (similar) one (thanks to
>> Tomas Hoger for pointing out): [1]
>> http://thread.gmane.org/gmane.comp.security.oss.general/8916/focus=8934
>>
>> 
[2] http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=695138#15
>> 
>> this time the CVE identifier should be allocated / issue is
>> valid, right?
>> 
>> While in the former [1], [2] case just the connection for the
>> user issuing the command would crash, this time (assuming) either
>> whole dovecot daemon might hang or even if the whole daemon
>> wouldn't hang (and request is handled within a thread), that
>> request would made the particular thread to consume excessive
>> amount of CPU due to infinite loop, right?
> 
> A logged in user can cause his own IMAP connection process to eat
> 100% CPU, so it won't immediately hang other users. By default
> users can log in max. 10 times from the same IP, so attacker
> requires many IPs to cause a real DoS. And of course a valid user
> account, which means it will be immediately visible to admin who is
> causing the system to slow down.
> 
>> Timo, can you confirm / disprove a CVE identifier should be
>> assigned to this?
> 
> I'm not against it, but I don't see this as that big of an issue,
> especially with v2.2 still not being widely used.

Yeah, we can't guarantee that can we. For all we know someone used it
in a major deployment/system image/who knows.

Please use CVE-2013-2111 for this issue.


- -- 
Kurt Seifried Red Hat Security Response Team (SRT)
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