MyCERT Advisories


MyCERT Advisories, Alerts and Summaries for the year 2017

MA-685.102017: MyCERT Advisory – WPA2 Key Reinstallation Vulnerabilities

Date first published: 17/10/2017


1.0    Introduction
A researcher has discovered vulnerabilities in WPA2, a protocol that secures all modern protected Wi-Fi networks. An attacker within range of a victim can exploit these weaknesses using Key Reinstallation attack (KRACK). Attackers can use this novel attack technique to read and steal sensitive information that was previously assumed to be safely encrypted such as credit card numbers, passwords, chat messages, emails, photos, etc.

The following Common Vulnerabilities and Exposures (CVE) identifiers were assigned to track which products are affected by specific instantiations of this key reinstallation attack:
•    CVE-2017-13077: Reinstallation of the pairwise encryption key (PTK-TK) in the 4-way handshake.
•    CVE-2017-13078: Reinstallation of the group key (GTK) in the 4-way handshake.
•    CVE-2017-13079: Reinstallation of the integrity group key (IGTK) in the 4-way handshake.
•    CVE-2017-13080: Reinstallation of the group key (GTK) in the group key handshake.
•    CVE-2017-13081: Reinstallation of the integrity group key (IGTK) in the group key handshake.
•    CVE-2017-13082: Accepting a retransmitted Fast BSS Transition (FT) Reassociation Request and reinstalling the pairwise encryption key (PTK-TK) while processing it.
•    CVE-2017-13084: Reinstallation of the STK key in the PeerKey handshake.
•    CVE-2017-13086: reinstallation of the Tunneled Direct-Link Setup (TDLS) PeerKey (TPK) key in the TDLS handshake.
•    CVE-2017-13087: reinstallation of the group key (GTK) when processing a Wireless Network Management (WNM) Sleep Mode Response frame.
•    CVE-2017-13088: reinstallation of the integrity group key (IGTK) when processing a Wireless Network Management (WNM) Sleep Mode Response frame.
Each of CVE identifier represents a specific instantiation of a key reinstallation attack. This means each CVE ID describes a specific protocol vulnerability, and therefore many vendors are affected by each individual CVE ID.


2.0    Impact
An attacker within the wireless communications range of an affected AP and client may exploit these vulnerabilities to conduct attacks that are dependent on the data confidentiality protocol being used. Impacts may include arbitrary packet decryption and injection, TCP connection hijacking, HTTP content injection, or the replay of unicast, broadcast, and multicast frames.


3.0 Affected Products
Devices with Wi-Fi connectivity using WPA and WPA2 protocols are potentially vulnerable.
Users and administrators can read vulnerability note VU#228519 of CERT/CC for additional details on which products are known to be affected.

•    https://www.kb.cert.org/vuls/id/228519
•    https://www.kb.cert.org/vuls/byvendor?searchview&Query=FIELD+Reference=228519&SearchOrder=4


4.0 Recommendations
Generally, MyCERT advises the users to patch all devices on your network with the latest security announcements by the vendor and follow best practice security policies to determine which updates should be applied.

As preventive measure, you should:

•    Where possible, use Ethernet cables and connect directly into the network, rather than using Wi-Fi.
•    Be wary of using Wi-Fi that you don’t personally administer until all patches and updates have been issued by vendors.
•    Consider browsing the web with an extension or browser add-on like (HTTPS Everywhere) that forces any site to encrypt your communication with website.
•    As an option to use the Internet, user can theter off their mobile device especially in higher-risk situations such as when traveling or working away from the office.
•    Organization can urge their staff to use corporate VPN for any WI-FI connections. While end user can consider using personal VPN for their own personal use.

For further enquiries, please contact MyCERT through the following channels:
E-mail: cyber999@cybersecurity.my or mycert@mycert.org.my
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5.0    References
•    http://www.kb.cert.org/vuls/id/228519
•    https://cwe.mitre.org/data/definitions/323.html
•    https://www.krackattacks.com/
•    https://papers.mathyvanhoef.com/ccs2017.pdf
•    https://securingthehuman.sans.org/blog/2017/10/16/28748/
•    https://www.kb.cert.org/vuls/byvendor?searchview&Query=FIELD+Reference=228519&SearchOrder=4