[UNIX] Hewlett Packard HP-UX Remote pfs_mountd.rpc Buffer Overflow Vulnerability

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Hewlett Packard HP-UX Remote pfs_mountd.rpc Buffer Overflow Vulnerability
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SUMMARY

PFS (the Portable File System) allows mounting of ISO 9660, High Sierra,
and Rock Ridge (ISO 9660 with Rock Ridge extensions) CD-ROM disks. The
daemon pfs_mountd.rpc is an RPC extension that is launched along with pfsd
in order to allow the easy mounting of these file systems under HP-UX. It
is remotely accessible over TCP and UDP.

Remote exploitation of a buffer overflow vulnerability in pfs_mountd.rpc
included in multiple versions of Hewlett Packard Co. HP-UX allows for
remote root access.

DETAILS

Vulnerable Systems:
* HP-UX version 11.11i.
* (It is suspected that previous versions are also vulnerable.)

If a remote user sends two specially crafted packets over UDP, the buffer
overflow is triggered. One must first send a call to procedure 5, and soon
thereafter send the actual payload to procedure 2. Due to the closed
nature of the pfs_mountd.rpc protocol specification, it is unclear at this
time what functions the respective procedures actually perform.

The seriousness of this vulnerability is reduced by the fact that in most
cases an attacker will only have one chance at exploitation until an
administrator restarts the crashed daemon after a failed attempt. However,
the attack is functional over UDP, thus allowing an attacker to completely
spoof the attack, possibly even making it appear from inside a trusted
network.

Workaround:
Adding firewall rules may not be enough to stop this attack due to the
fact that it can be spoofed.

Vendor Status:
Hewlett-Packard discontinued support for the PFS on March 1st, 2004. As a
solution to this vulnerability, Hewlett-Packard recommends discontinuing
the use of PFS. More information is available from HP Security Bulletin
HPSBUX02203 at the following URL.
http://www1.itrc.hp.com/service/cki/docDisplay.do?docId=c00913684

Disclosure Timeline:
* 10/25/2004 Initial vendor notification
* 10/25/2004 Initial vendor response
* 12/19/2005 Second vendor notification
* 01/30/2007 Third vendor notification
* 04/12/2007 Coordinated public disclosure


ADDITIONAL INFORMATION

The information has been provided by iDefense.
The original article can be found at:

<http://labs.idefense.com/intelligence/vulnerabilities/display.php?id=512>
http://labs.idefense.com/intelligence/vulnerabilities/display.php?id=512



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