[<prev] [next>] [<thread-prev] [day] [month] [year] [list]
Date: Tue, 23 Aug 2016 22:04:44 +0200
From: Salvatore Bonaccorso <carnil@...ian.org>
To: oss-security@...ts.openwall.com
Cc: Howard Guo <hguo@...e.com>, Marcus Meissner <meissner@...e.de>,
CVE Assignments MITRE <cve-assign@...re.org>
Subject: Re: cracklib: Stack-based buffer overflow when
parsing large GECOS field
Hi,
On Tue, Aug 16, 2016 at 03:34:54PM +0530, Huzaifa Sidhpurwala wrote:
> Hi All,
>
> A security flaw was reported to us by CSG Labs, details as follows:
>
> A stack-based overflow was found in the way cracklib, a library used to
> stop users from choosing easy to guess passwords, handled large GECOS
> field in the /etc/passwd file. When an application compiled against the
> cracklib libary, such as "passwd" is used to parse the GECOS field, it
> could cause the application to crash or execute arbitary code with the
> permissions of the user running such an application.
>
> To trigger the flaw, you need a specially-crafted "long" GECOS field,
> which can be done by a local user on the system. The attacker then needs
> to run some utility which uses cracklib to process this long GECOS field
> on the system. (such as "passwd" application which runs suid root)
>
> All versions of the cracklib library shipped with Red Hat Enterprise
> Linux are compiled with FORTIFY_SOURCE, which detects the
> buffer-overflow and aborts the application safely.
>
> Therefore the maximum impact of this flaw is application crash.
>
> However, there may be other applications, distributions which dont
> compile cracklib with FORTIFY_SOURCE, and this can lead to easy code
> exec or even privsec.
>
> A proposed patch is available at:
> https://bugzilla.redhat.com/attachment.cgi?id=1188599
>
> This flaw was assigned CVE-2016-6318 and it was previously disclosed via
> linux-distros mailing list.
In the SuSE Bugzilla, it was noted that there is still another buffer
overflow present, cf.
https://bugzilla.novell.com/show_bug.cgi?id=992966#c14
and the patch
https://build.opensuse.org/request/show/419768
> - Add patch 0004-overflow-processing-long-words.patch
> to fix a new buffer overflow identified together with bsc#992966.
[...]
> The input word is guaranteed to be at most STRINGSIZE-1 in length.
> One of the mangle operations involves duplicating the input word,
> resulting in a string twice the length to be accommodated by both
> area variables.
https://build.opensuse.org/package/view_file/Base:System/cracklib/0004-overflow-processing-long-words.patch
was applied.
Should that possibly get a further CVE id for reference?
Regards,
Salvatore
Powered by blists - more mailing lists
Please check out the
Open Source Software Security Wiki, which is counterpart to this
mailing list.
Confused about mailing lists and their use?
Read about mailing lists on Wikipedia
and check out these
guidelines on proper formatting of your messages.
