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AUSCERT External Security Bulletin Redistribution
ESB-2014.2473
Advisory (ICSA-14-353-01) Network Time Protocol Vulnerabilities
22 December 2014
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AusCERT Security Bulletin Summary
---------------------------------
Product: Network Time Protocol (NTP)
Publisher: ICS-CERT
Operating System: UNIX variants (UNIX, Linux, OSX)
Windows
Network Appliance
Impact/Access: Execute Arbitrary Code/Commands -- Remote/Unauthenticated
Access Privileged Data -- Existing Account
Denial of Service -- Remote/Unauthenticated
Provide Misleading Information -- Existing Account
Reduced Security -- Existing Account
Resolution: Patch/Upgrade
CVE Names: CVE-2014-9296 CVE-2014-9295 CVE-2014-9294
CVE-2014-9293
Reference: ESB-2014.2472
Original Bulletin:
https://ics-cert.us-cert.gov/advisories/ICSA-14-353-01
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Advisory (ICSA-14-353-01)
Network Time Protocol Vulnerabilities
Original release date: December 19, 2014
Legal Notice
All information products included in http://ics-cert.us-cert.gov are provided
"as is" for informational purposes only. The Department of Homeland Security
(DHS) does not provide any warranties of any kind regarding any information
contained within. DHS does not endorse any commercial product or service,
referenced in this product or otherwise. Further dissemination of this product
is governed by the Traffic Light Protocol (TLP) marking in the header. For
more information about TLP, see http://www.us-cert.gov/tlp/.
OVERVIEW
Google Security Team researchers Neel Mehta and Stephen Roettger have
coordinated multiple vulnerabilities with CERT/CC concerning the Network Time
Protocol (NTP). As NTP is widely used within operational Industrial Control
Systems deployments, NCCIC/ICS-CERT is providing this information for US
Critical Infrastructure asset owners and operators for awareness and to
identify mitigations for affected devices. ICS-CERT may release updates as
additional information becomes available.
These vulnerabilities could be exploited remotely. Exploits that target these
vulnerabilities are publicly available.
Products using NTP service prior to NTP-4.2.8 are affected. No specific vendor
is specified because this is an open source protocol.
IMPACT
Exploitation of these vulnerabilities could allow an attacker to execute
arbitrary code with the privileges of the ntpd process.
Impact to individual organizations depends on many factors that are unique to
each organization. ICS-CERT recommends that organizations evaluate the impact
of this vulnerability based on their operational environment, architecture,
and product implementation.
BACKGROUND
The NTP is described in RFC 958[a], an open source collaboration for acceptance
and is used to synchronize system time over a network.
VULNERABILITY CHARACTERIZATION
VULNERABILITY OVERVIEW
INSUFFICIENT ENTROPY[b]
If the authentication key is not set in the configuration file, ntpd will
generate a weak random key with insufficient entropy.
This vulnerability was resolved with NTP-dev4.2.7p11 on January 28, 2010.
CVE-2014-9293[c] has been assigned by CERT/CC to this vulnerability. A CVSS v2
base score of 7.3 has been assigned by CERT/CC; the CVSS vector string is
(AV:N/AC:L/Au:M/C:P/I:P/A:C).[d]
USE OF CRYPTOGRAPHICALLY WEAK PNRG[e]
Prior to NTP-4.2.7p230 ntp-keygen used a weak seed to prepare a random number
generator. The random numbers produced were then used to generate symmetric
keys.
This vulnerability was resolved with NTP-dev4.2.7p230 on November 1, 2010.
CVE-2014-9294[f] has been assigned by CERT/CC to this vulnerability. A CVSS v2
base score of 7.3 has been assigned; the CVSS vector string is
(AV:N/AC:L/Au:M/C:P/I:P/A:C).[g]
STACK-BASED BUFFER OVERFLOWS[h]
A remote attacker can send a carefully crafted packet that can overflow a
stack buffer and potentially allow malicious code to be executed with the
privilege level of the ntpd process. All NTP4 releases before 4.2.8 are
vulnerable.
This vulnerability is resolved with NTP-stable4.2.8 on December 19, 2014.
CVE-2014-9295[i] has been assigned by CERT/CC to this vulnerability. A CVSS v2
base score of 7.3 has been assigned; the CVSS vector string is
(AV:N/AC:L/Au:N/C:P/I:P/A:P).[j]
MISSING RETURN ON ERROR[k]
In the NTP code, a section of code is missing a return, and the resulting
error indicates processing did not stop. This indicated a specific rare error
occurred, which does not appear to affect system integrity. All NTP Version 4
releases before Version 4.2.8 are vulnerable.
This vulnerability is resolved with NTP-stable4.2.8 on December 19, 2014.
CVE-2014-9296[l] has been assigned by CERT/CC to this vulnerability. A CVSS v2
base score of 5.0 has been assigned; the CVSS vector string is
(AV:N/AC:L/Au:N/C:N/I:N/A:P).[m]
VULNERABILITY DETAILS
EXPLOITABILITY
These vulnerabilities could be exploited remotely.
EXISTENCE OF EXPLOIT
Exploits that target these vulnerabilities are publicly available.
DIFFICULTY
An attacker with a low skill would be able to exploit these vulnerabilities.
MITIGATION
All NTP Version 4 releases, prior to Version 4.2.8, are vulnerable and need to
be updated to Version 4.2.8.
ICS-CERT strongly encourages CIKR users to backup current operational ICS
configurations, and thoroughly test the updated software for system
compatibility on a test system before attempting deployment on operational
systems.
CERT/CC has published a Vulnerability Note at the following URL:
http://www.kb.cert.org/vuls/id/852879
The latest NTP releases can be accessed at:
http://support.ntp.org/bin/view/Main/SoftwareDownloads.
ICS-CERT would like to thank NTP for coordinating with the Google Security
Team Researchers.
ICS-CERT also encourages asset owners to take additional defensive measures to
protect against this and other cybersecurity risks.
Minimize network exposure for all control system devices and/or systems, and
ensure that they are not accessible from the Internet.
Locate control system networks and remote devices behind firewalls, and
isolate them from the business network.
When remote access is required, use secure methods, such as Virtual Private
Networks (VPNs), recognizing that VPNs may have vulnerabilities and should be
updated to the most current version available. Also recognize that VPN is only
as secure as the connected devices.
ICS-CERT also provides a section for control systems security recommended
practices on the ICS-CERT web page at:
http://ics-cert.us-cert.gov/content/recommended-practices. Several recommended
practices are available for reading and download, including Improving
Industrial Control Systems Cybersecurity with Defense-in-Depth Strategies.
ICS-CERT reminds organizations to perform proper impact analysis and risk
assessment prior to deploying defensive measures.
Additional mitigation guidance and recommended practices are publicly
available in the ICS-CERT Technical Information Paper,
ICS-TIP-12-146-01B--Targeted Cyber Intrusion Detection and Mitigation
Strategies, that is available for download from the ICS-CERT web site
(http://ics-cert.us-cert.gov/).
Organizations observing any suspected malicious activity should follow their
established internal procedures and report their findings to ICS-CERT for
tracking and correlation against other incidents.
a. Network Time Protocol (NTP), http://tools.ietf.org/html/rfc958, web site
last accessed December 19, 2014.
b. CWE-331: Insufficient Entropy,
http://cwe.mitre.org/data/definitions/331.html, web site last accessed
December 19, 2014.
c. NVD, http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2014-9293, NIST
uses this advisory to create the CVE web site report. This web site will be
active sometime after publication of this advisory.
d. CVSS Calculator,
http://nvd.nist.gov/cvss.cfm?version=2&vector=AV:N/AC:L/Au:M/C:P/I:P/A:C, web
site last accessed December 19, 2014.
e. CWE-338: Use of Cryptographically Weak Pseudo-Random Number Generator
(PRNG), http://cwe.mitre.org/data/definitions/338.html, web site last accessed
December 19, 2014.
f. NVD, http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2014-9294, NIST
uses this advisory to create the CVE web site report. This web site will be
active sometime after publication of this advisory.
g. CVSS Calculator,
http://nvd.nist.gov/cvss.cfm?version=2&vector=AV:N/AC:L/Au:M/C:P/I:P/A:C, web
site last accessed December 19, 2014.
h. CWE-121: Stack-Based Buffer Overflow,
http://cwe.mitre.org/data/definitions/121.html, web site last accessed
December 19, 2014.
i. NVD, http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2014-9295, NIST
uses this advisory to create the CVE web site report. This web site will be
active sometime after publication of this advisory.
j. CVSS Calculator,
http://nvd.nist.gov/cvss.cfm?version=2&vector=AV:N/AC:L/Au:N/C:P/I:P/A:P, web
site last accessed December 19, 2014.
k. CWE-389: Error Conditions, Return Values, Status Codes,
http://cwe.mitre.org/data/definitions/389.html, web site last accessed
December 19, 2014.
l. NVD, http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2014-9296, NIST
uses this advisory to create the CVE web site report. This web site will be
active sometime after publication of this advisory.
m. CVSS Calculator,
http://nvd.nist.gov/cvss.cfm?version=2&vector=AV:N/AC:L/Au:N/C:N/I:N/A:P, web
site last accessed December 19, 2014.
Contact Information
For any questions related to this report, please contact ICS-CERT at:
Email: ics-cert@hq.dhs.gov
Toll Free: 1-877-776-7585
International Callers: (208) 526-0900
For industrial control systems security information and incident reporting:
http://ics-cert.us-cert.gov
ICS-CERT continuously strives to improve its products and services. You can
help by choosing one of the links below to provide feedback about this
product.
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===========================================================================
Australian Computer Emergency Response Team
The University of Queensland
Brisbane
Qld 4072
Internet Email: auscert@auscert.org.au
Facsimile: (07) 3365 7031
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