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(SCO Releases Fix) Re: The Network Time Protocol Daemon (ntpd) Allows Remote Users to Execute Arbitrary Code on the Server - Typically to Gain Root Privileges on the Server
SecurityTracker Alert ID: 1001300|
SecurityTracker URL: http://securitytracker.com/id/1001300
(Links to External Site)
Date: Apr 12 2001
Execution of arbitrary code via network, Root access via network|
Fix Available: Yes Vendor Confirmed: Yes |
The Network Time Protocol Daemon (ntpd) shipped with many UNIX/Linux systems is reportedly vulnerable to a remote buffer overflow attack that allows remote users to execute arbitrary code on the server (potentially resulting in super-user access).|
The buffer overflow occurs when the daemon is building a response to a remote user's query that contains an overly large readvar argument. Because ntpd typically runs with root-level privileges, this can allow remote attackers to gain root access to the timeserver.
When exploited, the destination buffer is reportedly damaged by the attack, so any arbitrary shell code must be limited to less than approximately 70 bytes.
Code for a demonstration exploit is contained in the source message.
A remote user can cause arbitrary code supplied by the remote user to be executed on the target ntpd timeserver. Because ntpd typically runs with root-level privileges, this can result in remote root access being granted to the attacker. Because NTP is based on UDP, spoofing is possible, making protection against attacks more difficult.|
SCO reports that SCO OpenServer 5.0.0->5.0.6 is affected. The following patch should be applied: System Security Supplement (SSE) SSE073|
This patch can be obtained at: ftp://ftp.sco.com/SSE/sse073.tar.Z
See the source message for details.
UNIX (Open UNIX-SCO)|
This archive entry is a follow-up to the message listed below.|
Source Message Contents
Date: Wed, 11 Apr 2001 12:55:08 -0700|
Subject: SSE073: SCO OpenServer NTP buffer overflow fix
This is a multi-part message in MIME format.
Content-Type: text/plain; charset=us-ascii
TOPIC: NTP remote buffer overflow
PRODUCTS AFFECTED: SCO OpenServer 5.0.0->5.0.6
PATCH: System Security Supplement (SSE) SSE073
PATCH LOCATION: ftp://ftp.sco.com/SSE/sse073.tar.Z
SUMMARY: potentially exploitable buffer overflow fixed by SSE073
DATE: April 11, 2001
Content-Type: text/plain; charset=us-ascii;
System Security Enhancement (SSE) SSE073 - 11-Apr-2001
A buffer overflow was found by Przemyslaw Frasunek
<firstname.lastname@example.org> in the NTP daemon. Full exploit details
can be found in the BUGTRAQ archive
On SCO OpenServer 5 Release 5.0.6 systems, the NTP daemon is /etc/ntpd.
This exploit doesn't actually "work" on OpenServer. However, a small
effect can be observed.
To observe the effect, run ntpdc and give it the "ctlstats" command.
An exploit attempt registers as an increment of 2 to the
"requests received" and "responses sent" counters.
Running the fixed version of ntpd, an exploit attempt registers as +2
"requests received", +2 "responses sent", +1 "total bad pkts" and +1
"error msgs sent".
We find this difference sufficient to feel confident that the _specific_
problem has been corrected.
The patch is located at: ftp://ftp.sco.com/SSE/sse073.tar.Z
This patch is applicable to all releases of OpenServer 5.
However, the "install-sse073.sh" program to install the binary
can be used on Release 5.0.6 ONLY.
This patch contains a replacement for the /etc/ntpd binary in
Release 5.0.6. If you wish to use this binary on Releases 5.0.0
up to 5.0.5, you can install the binary manually. Note that
on these older releases, /etc/xntpd (based on NTPv3) was shipped
by default; hence, configuration files based on xntpd may have to
1. We reccommend you drop into single user mode to install this SSE
(though this is not enforced).
2. Uncompress and extract the SSE into a temporary directory
of the server (eg. /tmp/sse073).
# uncompress sse073.tar.Z
# tar xvf sse073.tar
3. Execute the install script. Follow the instructions
at the prompt.
Note: "Warning" messages simply explain that because a
specific file was not found on the current
server, it was not replaced. If a system has
custom binaries or paths, this patch may not
4. Clean up.
A backup of the orginal binaries will be saved in:
The following files will be left over after patch
installation and can be removed:
The following files will be left over after patch
installation and can be moved to an archival
directory in case the patches are needed again:
Checksums of the packages:
`sum -r ./sse073.tar`: 53459
`sum -r ./sse073.files.tar`: 61075
The vulnerability addressed in this patch was found by:
Przemyslaw Frasunek <email@example.com>
For more details, see the following BUGTRAQ archive:
SCO believes that this patch addresses the reported vulnerabilities.
However, in order that it be released as soon as possible, this patch
has not been fully tested or packaged to SCO's normal exacting
standards. For that reason, this patch is not officially supported.
Official supported and packaged fixes for current SCO products will
be available in due course.
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