Original release date: April 30, 2015

Systems Affected

Networked systems

Overview

Securing end-to-end communications plays an important role in protecting privacy and preventing some forms of man-in-the-middle (MITM) attacks. Recently, researchers described a MITM attack used to inject code, causing unsecured web browsers around the world to become unwitting participants in a distributed denial-of-service attack. That same code can be employed to deliver an exploit for a particular vulnerability or to take other arbitrary actions.

Description

A MITM attack occurs when a third party inserts itself between the communications of a client and a server. MITM attacks as a general class are not new. Classic MITM attacks (e.g., ARP Spoofing) focus on redirecting network communications. By definition, network infrastructure under attacker control is vulnerable to MITM. However, as technology evolves, new methods for performing MITM attacks evolve as well.

Currently, there is no single technology or configuration to prevent all MITM attacks. However, increasing the complexity with multiple layers of defense may raise the cost for the attacker. Increasing the attacker’s cost in time, effort, or money can be an effective deterrent to avoiding future network compromise.

Generally, encryption and digital certificates provide an effective safeguard against MITM attacks, assuring both the confidentiality and integrity of communications. As a result, modern MITM attacks have focused on taking advantage of weaknesses in the cryptographic infrastructure (e.g., certificate authorities (CAs), web browser certificate stores) or the encryption algorithms and protocols themselves.

Impact

MITM attacks are critical because of the wide range of potential impacts—these include the exposure of sensitive information, modification of trusted data, and injection of data.

Solution

Employing multiple network and browser protection methods forces an attacker to develop different tactics, techniques, and procedures to circumvent the new security configuration.

US-CERT recommends reviewing the following mitigations to reduce vulnerability to MITM attacks:

Update Transport Layer Security and Secure Socket Layer (TLS/SSL)

US-CERT recommends upgrading TLS to 1.1 or higher and ensuring TLS 1.0 and SSL 1, 2, 3.x are disabled, unless required. TLS 1.0 clients can fall back to version 3.0 of the SSL protocol, which is vulnerable to a padding oracle attack when Cypher-Block Chaining mode is used. This method is commonly referred to as the “POODLE” (Padding Oracle on Downgraded Legacy Encryption) attack. Vulnerable TLS implementations can be updated by applying the patch provided by the vendor. Vendor information is available in the National Vulnerability Database (NVD) entry for CVE-2014-3566 [1] or in CERT Vulnerability Note VU#577193 [2]. See US-CERT TA14-290A [3] for additional information on this vulnerability.

Utilize Certificate Pinning

Certificate pinning [4] is a method of associating X.509 certificate and its public key to a specific CA or root. Typically, certificates are validated by checking a verifiable chain of trust back to a trusted root certificate. Certificate pinning bypasses this validation process and allows the user to trust “this certificate only” or “trust only certificates signed by this certificate.” Please use the following resources to configure your browser for certificate pinning:

Microsoft Certificate Trust

The Microsoft Enhanced Mitigation Experience Toolkit (EMET) 5.2 employs a feature named “Certificate Trust” for SSL/TLS certificate pinning. This feature is intended to detect and stop MITM attacks that leverage Public Key Infrastructure. [5]

To use the Certificate Trust, you must provide a list of websites you want to protect and certificate pinning rules applicable to those websites. In order to do this, work with the Certificate Trust Configuration feature of the graphical application or use the Configuration Wizard to automatically configure EMET with the recommended settings. [6] Also, ensure period defaults are updated through patching.

Browser Certificate Pinning

Google Chrome and Mozilla Firefox, among others, perform certificate pinning. They conduct a variation of certificate pinning using the HTTP Strict Transport Security (HSTS), which pre-loads a specific set of public key hashes into the HSTS configuration, limiting valid certificates to only those with the specified indicated public key. Chrome uses HTTPS pins for most Google properties. It uses whitelisted public keys which include keys from Verisign, Google Internet Authority, Equifax, and GeoTrust. Thus, Chrome will not accept certificates for Google properties from other CAs.

Firefox 32 on desktop and later (Firefox 34 and later on Android) has the ability to use certificate pinning. It also has the ability to enforce built-in pinsets (mapping of public keys) information to domains. Firefox will pin all sites that Chrome already does, pin their own sites after audit and cleansing, and pin other popular sites that are already in good standing. Please visit this site on How to Use Pinning [7] and for more information.

Implement DNS-based Authentication of Named Entities (DANE)

DANE is a protocol that allows certificates (X.509) commonly used for TLS. DANE is bound to DNS which uses Domain Name System Security Extensions (DNSSEC). A working group in the Internet Engineering Task Force of DANE developed a new type of DNS record that allows a domain itself to sign statements about which entities are authorized to represent it. [8]

Google Chrome does not use DANE but uses an add-on [9] for support. Mozilla Firefox also uses an add-on [10] to check the existence and validity of DNSSEC.

Use Network Notary Servers

Network notary servers aim to improve the security of communications between computers and websites by enabling browsers to verify website authenticity without relying on CAs. CAs are often considered a security risk because they can be compromised. [11] As a result, browsers can deem fraudulent sites trustworthy and are left vulnerable to MITM attacks.

Each network notary server, or group of servers, is public and can be operated by public/private organizations or individuals. These servers regularly monitor websites and build a history of each site’s certificate data over time. When a browser equipped with a network notary add-on communicates with a website and obtains its certificate information, a user-designated network notary server supplies the browser with historical certificate data for that site. If certificate information provided by the website is inconsistent with the notary’s historical data, a MITM attack could be at play. [12]

References

• [1] https://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2014-3566
• [2] http://www.kb.cert.org/vuls/id/577193
• [3] https://www.us-cert.gov/ncas/alerts/TA14-290A
• [4] https://www.owasp.org/index.php/Certificate_and_Public_Key_Pinning
• [5] https://support.microsoft.com/en-us/kb/2458544
• [6] https://technet.microsoft.com/en-us/library/cc700843.aspx
• [7] https://wiki.mozilla.org/SecurityEngineering/Public_Key_Pinning
• [8] http://www.internetsociety.org/articles/dane-taking-tls-authentication-next-level-using-dnssec
• [9] http://www.internetsociety.org/deploy360/resources/how-to-add-dnssec-support-to-google-chrome/
• [10] https://www.dnssec-validator.cz/
• [11] http://perspectives-project.org/
• [12] http://arstechnica.com/information-technology/2008/08/network-notary-system-thwarts-man-in-the-middle-attacks/

Revision History

• April 30, 2015: Initial Release

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This product is provided subject to this Notification and this Privacy & Use policy.

Original release date: April 30, 2015

US-CERT warns users of potential email scams citing the earthquake in Nepal. The scam emails may contain links or attachments that may direct users to phishing or malware infected websites. Phishing emails and websites requesting donations for fraudulent charitable organizations commonly appear after these types of natural disasters.

US-CERT encourages users to take the following measures to protect themselves:

• Do not follow unsolicited web links or attachments in email messages.
• Maintain up-to-date antivirus software.
• Review the Federal Trade Commission’s Charity Checklist.
• Verify the legitimacy of the email by contacting the organization directly through a trusted contact number. Trusted contact    information can be found on the Better Business Bureau National Charity Report Index.
• Refer to the Security Tip (ST04-014) on Avoiding Social Engineering and Phishing Attacks for more information on social engineering attacks.

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This product is provided subject to this Notification and this Privacy & Use policy.

Original release date: April 29, 2015

Systems Affected

Systems running unpatched software from Adobe, Microsoft, Oracle, or OpenSSL. 

Overview

Cyber threat actors continue to exploit unpatched software to conduct attacks against critical infrastructure organizations. As many as 85 percent of targeted attacks are preventable [1].

This Alert provides information on the 30 most commonly exploited vulnerabilities used in these attacks, along with prevention and mitigation recommendations.

It is based on analysis completed by the Canadian Cyber Incident Response Centre (CCIRC) and was developed in collaboration with our partners from Canada, New Zealand, the United Kingdom, and the Australian Cyber Security Centre.

Description

Unpatched vulnerabilities allow malicious actors entry points into a network. A set of vulnerabilities are consistently targeted in observed attacks.

Impact

A successful network intrusion can have severe impacts, particularly if the compromise becomes public and sensitive information is exposed. Possible impacts include:

• Temporary or permanent loss of sensitive or proprietary information,
• Disruption to regular operations,
• Financial losses relating to restoring systems and files, and
• Potential harm to an organization’s reputation.

Solution

Maintain up-to-date software

The attack vectors frequently used by malicious actors such as email attachments, compromised “watering hole” websites, and other tools often rely on taking advantage of unpatched vulnerabilities found in widely used software applications. Patching is the process of repairing vulnerabilities found in these software components.

It is necessary for all organizations to establish a strong ongoing patch management process to ensure the proper preventive measures are taken against potential threats. The longer a system remains unpatched, the longer it is vulnerable to being compromised. Once a patch has been publicly released, the underlying vulnerability can be reverse engineered by malicious actors in order to create an exploit. This process has been documented to take anywhere from 24-hours to four days. Timely patching is one of the lowest cost yet most effective steps an organization can take to minimize its exposure to the threats facing its network.

Patch commonly exploited vulnerabilities

Executives should ensure their organization’s information security professionals have patched the following software vulnerabilities. Please see patching information for version specifics.

Microsoft

CVE	Affected Products	Patching Information
​CVE-2006-3227	​Internet Explorer	​Microsoft Malware Protection Encyclopedia Entry
CVE-2008-2244	Office Word	Microsoft Security Bulletin MS08-042
CVE-2009-3129	Office Office for Mac Open XML File Format Converter for Mac Office Excel Viewer Excel Office Compatibility Pack for Word, Excel, and PowerPoint	Microsoft Security Bulletin MS09-067
​CVE-2009-3674	​Internet Explorer	​Microsoft Security Bulletin MS09-072
CVE-2010-0806​	​Internet Explorer	​Microsoft Security Bulletin MS10-018
CVE-2010-3333	Office Office for Mac Open XML File Format Converter for Mac	Microsoft Security Bulletin MS10-087
CVE-2011-0101	Excel	Microsoft Security Bulletin MS11-021
CVE-2012-0158	Office SQL Server BizTalk Server Commerce Server Visual FoxPro Visual Basic	Microsoft Security Bulletin MS12-027
CVE-2012-1856	Office SQL Server Commerce Server Host Integration Server Visual FoxPro Visual Basic	Microsoft Security Bulletin MS12-060
​CVE-2012-4792	​Internet Explorer	​Microsoft Security Bulletin MS13-008
CVE-2013-0074​	​Silverlight and Developer Runtime	​Microsoft Security Bulletin MS13-022
CVE-2013-1347	​Internet Explorer	​Microsoft Security Bulletin MS13-038
CVE-2014-0322​	​​Internet Explorer	​Microsoft Security Bulletin MS14-012
CVE-2014-1761	Microsoft Word Office Word Viewer Office Compatibility Pack Office for Mac Word Automation Services on SharePoint Server Office Web Apps Office Web Apps Server	Microsoft Security Bulletin MS14-017
​CVE-2014-1776	​Internet Explorer	​Microsoft Security Bulletin MS14-021
CVE-2014-4114	​Windows	​Microsoft Security Bulletin MS14-060

OpenSSL

CVE	Affected Product	Patching Information
CVE-2014-0160	OpenSSL	CERT Vulnerability Note VU#720951

Implement the following four mitigation strategies.

As part of a comprehensive security strategy, network administrators should implement the following four mitigation strategies, which can help prevent targeted cyber attacks.

It is recommended that users review US-CERT Security Tip (ST13-003) and CCIRC’s Mitigation Guidelines for Advanced Persistent Threats for additional background information and to assist in the detection of, response to, and recovery from malicious activity linked to advance persistent threats [2, 3].

References

• [1] Canadian Cyber Incident Response Centre, Top 4 Strategies to Mitigate Targeted Cyber Intrusions
• [2] Canadian Cyber Incident Response Centre, TR11-002, Mitigation Guidelines for Advanced Persistent Threats
• [3] US-CERT Security Tip (ST13-003): Handling Destructive Malware

Revision History

• April 29, 2015: Initial release

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This product is provided subject to this Notification and this Privacy & Use policy.

Original release date: April 27, 2015

The US-CERT Cyber Security Bulletin provides a summary of new vulnerabilities that have been recorded by the National Institute of Standards and Technology (NIST) National Vulnerability Database (NVD) in the past week. The NVD is sponsored by the Department of Homeland Security (DHS) National Cybersecurity and Communications Integration Center (NCCIC) / United States Computer Emergency Readiness Team (US-CERT). For modified or updated entries, please visit the NVD, which contains historical vulnerability information.

The vulnerabilities are based on the CVE vulnerability naming standard and are organized according to severity, determined by the Common Vulnerability Scoring System (CVSS) standard. The division of high, medium, and low severities correspond to the following scores:

• High – Vulnerabilities will be labeled High severity if they have a CVSS base score of 7.0 – 10.0

• Medium – Vulnerabilities will be labeled Medium severity if they have a CVSS base score of 4.0 – 6.9

• Low – Vulnerabilities will be labeled Low severity if they have a CVSS base score of 0.0 – 3.9

Entries may include additional information provided by organizations and efforts sponsored by US-CERT. This information may include identifying information, values, definitions, and related links. Patch information is provided when available. Please note that some of the information in the bulletins is compiled from external, open source reports and is not a direct result of US-CERT analysis.

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This product is provided subject to this Notification and this Privacy & Use policy.

Original release date: April 23, 2015

WordPress 4.1.2 has been released to address multiple vulnerabilities, one of which could allow a site to be compromised by a remote attacker. WordPress 4.1.1 and earlier are affected by this vulnerability.

US-CERT recommends users and administrators review the WordPress Security Release and apply the necessary updates.

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This product is provided subject to this Notification and this Privacy & Use policy.

Original release date: April 21, 2015

The Internet Crime Complaint Center (IC3) has issued an alert warning that law enforcement personnel and public officials may be at an increased risk of cyber attacks. Doxing—the act of gathering and publishing individuals’ personal information without permission—has been observed. Hacking collectives may exploit publicly available information identifying officers or officials, their employers, and their families. These target groups should protect their online presence and exposure.

Users are encouraged to review the IC3 Alert for details and refer to US-CERT Tip ST06-003 for information on staying safe on social network sites.

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This product is provided subject to this Notification and this Privacy & Use policy.

Original release date: April 20, 2015

The US-CERT Cyber Security Bulletin provides a summary of new vulnerabilities that have been recorded by the National Institute of Standards and Technology (NIST) National Vulnerability Database (NVD) in the past week. The NVD is sponsored by the Department of Homeland Security (DHS) National Cybersecurity and Communications Integration Center (NCCIC) / United States Computer Emergency Readiness Team (US-CERT). For modified or updated entries, please visit the NVD, which contains historical vulnerability information.

The vulnerabilities are based on the CVE vulnerability naming standard and are organized according to severity, determined by the Common Vulnerability Scoring System (CVSS) standard. The division of high, medium, and low severities correspond to the following scores:

• High – Vulnerabilities will be labeled High severity if they have a CVSS base score of 7.0 – 10.0

• Medium – Vulnerabilities will be labeled Medium severity if they have a CVSS base score of 4.0 – 6.9

• Low – Vulnerabilities will be labeled Low severity if they have a CVSS base score of 0.0 – 3.9

Entries may include additional information provided by organizations and efforts sponsored by US-CERT. This information may include identifying information, values, definitions, and related links. Patch information is provided when available. Please note that some of the information in the bulletins is compiled from external, open source reports and is not a direct result of US-CERT analysis.

 

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This product is provided subject to this Notification and this Privacy & Use policy.

Original release date: April 15, 2015 | Last revised: April 16, 2015

Oracle has released security fixes to address 98 vulnerabilities as part of its quarterly Critical Patch Update. Exploitation of some of these vulnerabilities may allow a remote attacker to take control of an affected system.

Users and administrators are encouraged to review the Oracle April 2015 Critical Patch Update and apply the necessary updates.

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This product is provided subject to this Notification and this Privacy & Use policy.

Original release date: April 15, 2015

Google has released Chrome 42.0.2311.90 for Windows, Mac, and Linux to address multiple vulnerabilities. Exploitation of one of these vulnerabilities may allow a remote attacker to take control of an affected system.

US-CERT encourages users and administrators to review the Google Chrome blog entry and apply the necessary updates.

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This product is provided subject to this Notification and this Privacy & Use policy.

Original release date: April 15, 2015

Systems Affected

Microsoft Windows

Overview

The Simda botnet – a network of computers infected with self-propagating malware – has compromised more than 770,000 computers worldwide [1].

The United States Department of Homeland Security (DHS), in collaboration with Interpol and the Federal Bureau of Investigation (FBI), has released this Technical Alert to provide further information about the Simda botnet, along with prevention and mitigation recommendations.

Description

Since 2009, cyber criminals have been targeting computers with unpatched software and compromising them with Simda malware [2]. This malware may re-route a user’s Internet traffic to websites under criminal control or can be used to install additional malware. 

The malicious actors control the network of compromised systems (botnet) through backdoors, giving them remote access to carry out additional attacks or to “sell” control of the botnet to other criminals [1]. The backdoors also morph their presence every few hours, allowing low anti-virus detection rates and the means for stealthy operation [3].    

Impact

A system infected with Simda may allow cyber criminals to harvest user credentials, including banking information; install additional malware; or cause other malicious attacks. The breadth of infected systems allows Simda operators flexibility to load custom features tailored to individual targets.

Solution

Users are recommended to take the following actions to remediate Simda infections:

• Use and maintain anti-virus software – Anti-virus software recognizes and protects your computer against most known viruses. It is important to keep your anti-virus software up-to-date (see Understanding Anti-Virus Software for more information).
• Change your passwords – Your original passwords may have been compromised during the infection, so you should change them (see Choosing and Protecting Passwords for more information).
• Keep your operating system and application software up-to-date – Install software patches so that attackers cannot take advantage of known problems or vulnerabilities. Many operating systems offer automatic updates. If this option is available, you should enable it (see Understanding Patches for more information).
• Use anti-malware tools – Using a legitimate program that identifies and removes malware can help eliminate an infection. Users can consider employing a remediation tool (examples below) that will help with the removal of Simda from your system.

          Kaspersky Lab : http://www.kaspersky.com/security-scan

          Microsoft: http://www.microsoft.com/security/scanner/en-us/default.aspx

          Trend Micro: http://housecall.trendmicro.com/

• Check to see if your system is infected – The link below offers a simplified check for beginners and a manual check for experts.

          Cyber Defense Institute:  http://www.cyberdefense.jp/simda/

The above are examples only and do not constitute an exhaustive list. The U.S. government does not endorse or support any particular product or vendor.

References

• [1] INTERPOL Coordinates Global Operation to Take Down Simda Botnet
• [2] Microsoft partners with Interpol, industry to disrupt global malware attack affecting more than 770,000 PCs in past six mo
• [3] Botnet that Enslaved 770,000 PCs Worldwide Comes Crashing Down

Revision History

• April 15, 2015: Initial Release

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This product is provided subject to this Notification and this Privacy & Use policy.