U.S. Flag Official website of the Department of Homeland Security
U.S. Department of Homeland Security Seal. ICS-CERT. Industrial Control Systems Cyber Emergency Response Team.
TLP:WHITE

Advisory (ICSA-14-353-01C)

Network Time Protocol Vulnerabilities (Update C)

Original release date: February 05, 2015 | Last revised: February 09, 2015

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

This updated advisory is a follow-up to the updated advisory titled ICSA-14-353-01B Network Time Protocol Vulnerabilities that was published February 4, 2015, on the NCCIC/ICS-CERT web site.

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, 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.

Products using NTP service prior to ntp-4.2.8p1 are affected. This is an open source protocol.

--------- Begin Update C Part 1 of 1 --------

ICS-CERT sent out a query to vendors we have collaborated with in the past to develop a list of known impacted products. Over 20 vendors have responded back with information regarding if their products are affected by this NTP vulnerability. ICS-CERT has created a supplement to this advisory that contains vendor-supplied affected product information, which will be updated as new information is received, without updating this advisory. This supplement can be found at the following web location: https://ics-cert.us-cert.gov/advisories/ICSA-14-353-01-Supplement.

--------- End Update C Part 1 of 1 ----------

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

NTP is described in RFC 958,a 1305,b and 5905c; IETF Standards documents that describe the protocol and algorithms used to synchronize time over a network. The reference implementation of these Standards comes from the open source project via the University of Delaware and Network Time Foundation, and is in wide use.

VULNERABILITY CHARACTERIZATION

VULNERABILITY OVERVIEW

INSUFFICIENT ENTROPYd

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-2014-9293e 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).f

USE OF CRYPTOGRAPHICALLY WEAK PRNGg

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-2014-9294h 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).i

STACK-BASED BUFFER OVERFLOWSj

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-2014-9295k has been assigned by CERT/CC to this vulnerability. A CVSS v2 base score of 7.5 has been assigned; the CVSS vector string is (AV:N/AC:L/Au:N/C:P/I:P/A:P).l

MISSING RETURN ON ERRORm

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-2014-9296n 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).o

AUTHENTICATION BYPASS BY SPOOFINGp

The IPv6 address ::1 can be spoofed, allowing an attacker to bypass access control lists (ACLs) based on ::1. All NTP4 releases before 4.2.8 are vulnerable. Linux and slightly older Mac OSX kernels are vulnerable, but other tested OSes are not vulnerable to the ::1 spoofing. Proper firewall rulings can mitigate this problem. As this issue may be a kernel issue, rather than NTPD, source-IP based ACLs may be vulnerable as well.

This vulnerability is resolved with NTP-stable4.2.8p1 on February 04, 2014.

CVE-2014-9297q has been assigned by CERT/CC to this vulnerability. A CVSS v2 base score of 9.0 has been assigned; the CVSS vector string is (AV:N/AC:L/Au:N/C:P/I:P/A:C).r

IMPROPER CHECK FOR UNUSUAL OR EXCEPTIONAL CONDITIONSs

The length value in extension field pointers is not properly validated, allowing information leaks. All NTP Version 4 releases before Version 4.2.8 are vulnerable.

This vulnerability is resolved with NTP-stable4.2.8p1 on February 04, 2015.

CVE-2014-9298t has been assigned by CERT/CC to this vulnerability. A CVSS v2 base score of 7.5 has been assigned; the CVSS vector string is (AV:N/AC:L/Au:N/C:P/I:P/A:P).u

VULNERABILITY DETAILS

EXPLOITABILITY

These vulnerabilities could be exploited remotely.

EXISTENCE OF EXPLOIT

No known public exploits specifically target these vulnerabilities.

DIFFICULTY

An attacker with a low skill and an exploit script would be able to exploit these vulnerabilities. However, a higher-level of skill would be necessary to craft usable exploit scripts.

MITIGATION

All NTP Version 4 releases, prior to Version 4.2.8p1, are vulnerable and need to be updated to Version 4.2.8p1.

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

ICS-CERT would like to thank Network Time Foundations’ NTP Project for coordinating with the Google Security Team Researchers.

The latest NTP security information and software releases can be accessed at:

http://support.ntp.org/Main/SecurityNotice

http://support.ntp.org/bin/view/Main/SoftwareDownloads.

The NTP project recommends updating firewall rules to disallow ::1 packets from incoming physical Ethernet ports (mitigation for CVE-2014-9297).

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.

Additional mitigation guidance and recommended practices are publicly available in the following two publications:

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.

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.


Contact Information

For any questions related to this report, please contact the NCCIC at:

Email: NCCICCUSTOMERSERVICE@hq.dhs.gov
Toll Free: 1-888-282-0870

For industrial control systems cybersecurity information:  http://ics-cert.us-cert.gov 
or incident reporting:  https://ics-cert.us-cert.gov/Report-Incident?

The NCCIC continuously strives to improve its products and services. You can help by choosing one of the links below to provide feedback about this product.

Was this document helpful?  Yes  |  Somewhat  |  No

Back to Top