Re: HPUX security bulletins digest

["Hobbs, Eric (Sbcsi)" <EHobbs () CORP SBC COM>]

Hi.

I'm not so sure about the remote compromise, but the /sbin/auto_parms
script, which I believe is fixed by this patch, contains at least two
instances where it sources files in the /tmp directory without checking for
their existence first.

I'm pulling this out of my memory because I notified HP of some of these
problems about four months ago, so my details might be prone to fuzzy math.
I don't have my original document with me at the moment.

One instance is more of a guessing game.  When booting, the /etc/rc script
calls the /etc/auto_parms script to work out some DHCP details. During this
process, I believe it pulls some environment vars out of
/etc/rc.config.d/netconf and creates a file in /tmp called $$.sh

Since this script is called at boot time, a nasty local user can guess a
range of PIDs that could be used and can create a series of soft links or
named pipes in /tmp that could either blow away a file in the first case, or
completely freeze the boot process in the second case.  DoS.

The second problem that I found was more serious.  In the auto_parms script,
there is a chunk of code that apparently is only supposed to be used when
booting during an installation.  It checks for the existence of a file
called /tmp/install.vars.  If it is there, it sources it on boot up. Use
your imagination.  The bad user can drop a file in there that will give them
a rootshell when the system is rebooted. Very bad. I tried it. It worked.

While I'm sure the HP patch resolves it, I found that because I don't use
DHCP, I just renamed the /sbin/auto_parms script.  /sbin/rc complains a
little bit on boot, but otherwise, it didn't affect my machines.

Also:  MAKE SURE THE STICKY BIT IS SET ON /TMP!!!  Even the TCB HP-UX
doesn't do this.  It seems like a major oversight.

So yes, it is a problem, but I'm not a black-hat h4Ck3R/cR4cK3R type so I
don't know if the problems can be leveraged to open a remote compromise.

Sorry for the vagueness,

--Eric

-----Original Message-----
From: Boyce, Nick [mailto:nick.boyce () EDS COM]
Sent: Monday, November 13, 2000 3:38 PM
To: BUGTRAQ () SECURITYFOCUS COM
Subject: Re: HPUX security bulletins digest


I'm confused  <g> ... the HP alert indicates that problem "HPSBUX0011-130"
is both a "DoS at boot-time" problem, and a remote root compromise - [see
"DAMAGE" and "Background" below].

So which is it ?   Maybe it's both, but if it's just boot-time DoS I can
live with that for a spell.

The man page says :
      auto_parms is a system initialization script whose primary
      responsibility lies in handling first time boot configuration and
      ongoing management of the DHCP lease(s).

The script is 1700 lines long, so I don't want to have to try to analyse it
myself.  Since it deals with DHCP address requesting, I suppose it may be
vulnerable to something like the recent ISC DHCP client vulnerability (if
there exists a malicious DHCP server somewhere), but HP don't give any
clues.

Does anyone understand this better than me ?
[It matters a bit to me - many systems to fix - as to quite how much panic I
allow myself ...]

I'd log a call with HP to ask, but I've not had a useful result from that
course in the past.

Thanks,
Nick
EDS Healthcare, Bristol, UK


-----Original Message-----
From: Oonk, Patrick [mailto:patrick () PINE NL]
Sent: 13 November 2000 13:22
To: BUGTRAQ () SECURITYFOCUS COM
Subject: security bulletins digest

                        HP Support Information Digests

[snip]

Document ID      Title
---------------  -----------
HPSBUX0011-130   Sec. Vulnerability in auto_parms

[snip]

DAMAGE:   May allow remote users to gain root access or to disrupt
          normal operations.

[snip]

   A. Background
      Hewlett-Packard Company has been informed of a defect in the
      /sbin/auto_parms script.  There is potential for a Denial of
      Service (DoS) at boot time.

[end-of-alert-and-snippage]