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(CIAC Issues Advisory) 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: 1001357|
SecurityTracker URL: http://securitytracker.com/id/1001357
(Links to External Site)
Date: Apr 18 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.|
CIAC has issued an advisory (http://www.ciac.org/ciac/bulletins/l-071.shtml), as have most of the applicable vendors. See the Message History in this alert to access the individual vendor advisories.|
Linux (Any), UNIX (Any)|
This archive entry is a follow-up to the message listed below.|
Source Message Contents
Date: Tue, 17 Apr 2001 07:59:02 -0700 (PDT)|
Subject: CIAC Bulletin L-071: Network Time Protocol (NTP) Vulnerabilities
[ For Public Release ]
-----BEGIN PGP SIGNED MESSAGE-----
The U.S. Department of Energy
Computer Incident Advisory Center
___ __ __ _ ___
/ | /_\ /
\___ __|__ / \ \___
Network Time Protocol (NTP) Vulnerabilities
April 17, 2001 18:00 GMT Number L-071
PROBLEM: The Network Time Protocol (NTP) codes of certain vendors are
vulnerable to a buffer overflow attack.
HP9000 Series 700/800 running HP-UX releases 10.XX and 11.XX.
Red Hat Linux 6.2 and earlier (for xntpd).
Red Hat Linux 7.0 (for ntpd).
NetBSD prior to 1.4.
NetBSD 1.4 and 1.5.
NetBSD-CURRENT prior to 2001-04-05.
FreeBSD 3.x (all releases).
FreeBSD 4.x (all releases).
FreeBSD 3.5-STABLE and 4.2-STABLE prior to the correction
FreeBSD ports collection prior to the correction date
OpenLinux 2.3 (All packages previous to xntp-3.5.93e-5)
OpenLinux eServer 2.3.1 and OpenLinux eBuilder (All packages
previous to xntp-3.5.93e-5)
OpenLinux eDesktop 2.4 (All packages previous to
DAMAGE: A remote intruder can use the buffer overflow to cause the NTP
code to crash. It is possible that the buffer overflow can be
used to execute arbritrary code. If the NTP daemon is running
as root, then this could lead to a root compromise.
SOLUTION: Obtain your particular vendorís directions from the vendorís
web site and follow the vendorís suggestions.
VULNERABILITY The risk is HIGH. The listed vendors have determined that their
ASSESSMENT: codes are vulnerable. The vulnerabilities and detailed exploits
have been discussed in public forums.
CIAC wishes to acknowledge the contributions of Hewlett-Packard, Red Hat,
NetBSD, FreeBSD, and Caldera for the information contained in this bulletin.
CIAC, the Computer Incident Advisory Capability, is the computer
security incident response team for the U.S. Department of Energy
(DOE) and the emergency backup response team for the National
Institutes of Health (NIH). CIAC is located at the Lawrence Livermore
National Laboratory in Livermore, California. CIAC is also a founding
member of FIRST, the Forum of Incident Response and Security Teams, a
global organization established to foster cooperation and coordination
among computer security teams worldwide.
CIAC services are available to DOE, DOE contractors, and the NIH. CIAC
can be contacted at:
Voice: +1 925-422-8193 (7x24)
FAX: +1 925-423-8002
STU-III: +1 925-423-2604
Previous CIAC notices, anti-virus software, and other information are
available from the CIAC Computer Security Archive.
World Wide Web: http://www.ciac.org/
(or http://ciac.llnl.gov -- they're the same machine)
Anonymous FTP: ftp.ciac.org
(or ciac.llnl.gov -- they're the same machine)
PLEASE NOTE: Many users outside of the DOE, ESnet, and NIH computing
communities receive CIAC bulletins. If you are not part of these
communities, please contact your agency's response team to report
incidents. Your agency's team will coordinate with CIAC. The Forum of
Incident Response and Security Teams (FIRST) is a world-wide
organization. A list of FIRST member organizations and their
constituencies can be obtained via WWW at http://www.first.org/.
This document was prepared as an account of work sponsored by an
agency of the United States Government. Neither the United States
Government nor the University of California nor any of their
employees, makes any warranty, express or implied, or assumes any
legal liability or responsibility for the accuracy, completeness, or
usefulness of any information, apparatus, product, or process
disclosed, or represents that its use would not infringe privately
owned rights. Reference herein to any specific commercial products,
process, or service by trade name, trademark, manufacturer, or
otherwise, does not necessarily constitute or imply its endorsement,
recommendation or favoring by the United States Government or the
University of California. The views and opinions of authors expressed
herein do not necessarily state or reflect those of the United States
Government or the University of California, and shall not be used for
advertising or product endorsement purposes.
LAST 10 CIAC BULLETINS ISSUED (Previous bulletins available from CIAC)
L-061: Microsoft IE can Divulge Location of Cached Content
L-062: Erroneous Verisign-Issued Digital Certificates for Microsoft
L-063: RedHat Linux Log Code Buffer Overflow/Unguarded Browser Call
l-064: The Lion Internet Worm DDOS Risk
L-065: Solaris Exploitation of snmpXdmid
L-066: Internet Explorer MIME Mime Header Vulnerability
L-067: Linux worm Adore
L-068: Cisco VPN3000 Concentrator TELNET Vulnerability
L-069: Cisco Content Services Switch User Account Vulnerability
L-070: FTP Filename Expansion Vulnerability
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Version: 4.0 Business Edition
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