WPA2 KRACK Vulnerability – Part 1

On Sunday, October 15th, 2017, the information located at https://www.krackattacks.com was made public notifying the world of a vulnerability that had been discovered in the WPA2 wireless protocol. Below is the contents of an email I sent to customers this morning. I’m posting it here in hopes that you will find it useful in determining exactly what all this means for you. I will post additional updates as I learn more and as more information comes available from various sources.


Executive Summary

No unpatched wireless client will ever be safe from exploit. This includes everything from your laptop, phone, and tablet all the way down to your WiFi enabled thermostat and light bulbs.

  • There are a number of statements that I can make to downplay the seriousness of this issue, but at the end of the day the above statement is correct.
  • Although wireless vendors are providing updates for wireless access points, updating wireless access points with new software does not in any way fix the problem (one caveat does apply, see quick tech. summary ***).
  • Wireless client devices must be updated in order to be 100% certain that your data is secure.
  • Due to the nature of the vulnerability, the likelihood of your data being exploited at home or at work is minimal, but the possibility still exists.
  • The only way to be 100% your data is not compromised on an unpatched device is to disable WiFi and use cellular data. This is especially true when using your device in public.


Quick Technical Summary

  • Data transmitted over SSL/TLS (secure tunnel) remains secure even on unpatched devices as long as the client application validates the SSL/TLS certificate and does not use broken SSL/TLS versions. The use of Office 365 should remain secure. If something on your device warns you of an invalid certificate or something similar, stop what you are doing and contact support.
  • Unpatched devices can leverage the use of a corporate VPN or a VPN service to secure data over the wireless network. Please note that over 75% of the VPN services available on the Apple Store and Google Play are not security rated services.
  • There are 10 specific vulnerabilities that have been identified and assigned CVE identifiers (listed below the detailed technical summary). Different devices are susceptible to some or all of these vulnerabilities depending on the way the software that runs the wireless client was developed (ie, their interpretation and implementation of the Wi-Fi Standard).
  • Proximity is a saving grace, but you’re still vulnerable. An attack on Android devices was demonstrated on KrackAttacks.com, and is limited in success by the proximity of the attacker. The attacker must be closer to the victim than the victim is to the wireless access point they are connected to in order for the exploit to work. This is why many people are discounting the seriousness of the exploit because normally you would notice someone “strange” at home or at work who may be using a laptop to exploit your device. This is a rationalization to make people feel comfortable and a poor reason to not be concerned. It needs to be remembered that while difficult, it is still possible.
  • I personally have a Honeywell WiFi enabled thermostat at my home. This device will most likely never receive a software update from Honeywell and will always be exploitable. It’s not a grave concern to me, but it is still an exploitable device that I will be keeping an eye, especially as more information comes to light over the next weeks, months, and years on how these exploits are eventually leveraged by malicious attackers. Time will tell whether I need to replace the device or just live with it.
  • (***)The caveat to the statement in the executive summary regarding wireless access point software updates is this:
    • Wireless access points used in mesh type networks do need to be updated as they operate as both wireless access point and client.
    • For this reason all Ubiquiti UniFi access points serviced by Skyhawk’s Hosted UniFi controller have been updated to the latest version that includes the STA fix. Customers with on premise UniFi Controllers are in the process of being updated. Cisco Meraki access points have also already received necessary updates. Further updates for wireless point-to-point links will be made as information becomes available from vendors on firmware upgrades.


Vendor Specific Notes

  • Microsoft
    • Updates for all versions of Windows, from Windows XP to Windows 10, was released on Tuesday October 10, 2017
    • To verify that your Microsoft Windows computer is updated, check your update list and verify that it contains the 2017-10 Cumulative Update.
  • Apple
    • While no official update has come from the company, one individual with “close ties” to Apple has reported that BETA versions of all Apple operating systems contain the necessary updates. No timeline has currently been presented as to when these updates will be included in the mainstream updates.
    • The statement has been made that Apple devices are more difficult to exploit than other devices on the market. This is based on data in the initial vulnerability discovery paper. This simply means that the Apple implementations have less bugs in them are not susceptible to all 10 of the CVEs. You should be aware however that they are still exploitable currently.
  • Android Devices
    • All Android devices running version 6.0 and higher are particularly susceptible to the most trivial attack, the all-zero encryption key exploit.
    • Android phones are going to be a special issue as updates do not come directly from the manufacturer, but rather come from the cellular provider. It is anticipated that this will delay the availability of updates for Android phones significantly. It is recommended to disable WiFi and switch to using cellular data where possible to ensure data security.
  • Additional vendor updates can be found here: https://github.com/kristate/krackinfo


Detailed Technical Summary

Start with the information posted at https://www.krackattacks.com/, especially their Q&A section. For really technical information so the site listed immediately below.

The most comprehensive technical review I’ve come across of the 10 vulnerabilities outlined can be found in the link below.


The 10 Vulnerabilities

These are the Common Vulnerabilities and Exposures (CVE) identifiers that were assigned to track which products are affected by specific instantiations of the key reinstallation attack. These are included here as a reference for the very technically curious.

  • 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.

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