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ESB-2014.2473 - [Win][UNIX/Linux][Appliance] Network Time Protocol (NTP): Multiple vulnerabilities

Date: 22 December 2014
References: ESB-2014.2472  ESB-2014.2476  ESB-2014.2497  ESB-2014.2519  ESB-2015.0006  ESB-2015.0008  ESB-2015.0029  ESB-2015.0341  ESB-2015.0363  ESB-2015.0421  
ESB-2015.0422.2  ESB-2015.0535  ESB-2015.0705  ESB-2015.0715  ESB-2015.2648  ESB-2015.3089  

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===========================================================================
             AUSCERT External Security Bulletin Redistribution

                               ESB-2014.2473
      Advisory (ICSA-14-353-01) Network Time Protocol Vulnerabilities
                             22 December 2014

===========================================================================

        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

- --------------------------BEGIN INCLUDED TEXT--------------------

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.

- --------------------------END INCLUDED TEXT--------------------

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NOTE: Third Party Rights
This security bulletin is provided as a service to AusCERT's members.  As
AusCERT did not write the document quoted above, AusCERT has had no control
over its content. The decision to follow or act on information or advice
contained in this security bulletin is the responsibility of each user or
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which may arise from following or acting on information or advice contained in
this security bulletin.

NOTE: This is only the original release of the security bulletin.  It may
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Previous advisories and external security bulletins can be retrieved from:

        http://www.auscert.org.au/render.html?cid=1980

===========================================================================
Australian Computer Emergency Response Team
The University of Queensland
Brisbane
Qld 4072

Internet Email: auscert@auscert.org.au
Facsimile:      (07) 3365 7031
Telephone:      (07) 3365 4417 (International: +61 7 3365 4417)
                AusCERT personnel answer during Queensland business hours
                which are GMT+10:00 (AEST).
                On call after hours for member emergencies only.
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