WPA2 “KRACK” – Technical notes

Tuesday, October 17th, 2017 | Jim Cheetham | Comments Off on WPA2 “KRACK” – Technical notes

KRACK (Key Reinstallation Attacks) is an effective attack on the WPA2 802.11i protocol used for protecting WiFi networks, published on October 16 2017 .

Because it is an attack on the protocol itself, every piece of equipment that can communicate over WiFi is affected. The attack must be carried out by a device that is in range of the network; i.e. this is a local attack, not a remote one.


Be WORRIED, but there is no need to PANIC. If there is a PATCH for your device, apply it as soon as possible. Otherwise, worry until there is.

KRACK tricks your wireless devices into resetting their encryption sessions to a known state, after which the attacker can read everything that they do, and can inject their own data into the network (i.e. a Man-in-the-Middle attack). This effectively turns your “private, secure” WPA2 network into a “public, insecure” one.

If you are safe operating your device on a public insecure network (e.g. airport or coffee-shop WiFi), then you will be equally safe operating it on a compromised WPA2 network.

KRACK does NOT steal your WiFi passwords or credentials.

The only effective fix for KRACK is on your client devices. PCs and laptops are likely to be patched quickly, mobile phones much more slowly if at all, and IoT devices are at serious risk.

KRACK References

  • KRACK website, https://www.krackattacks.com/
  • Key Reinstallation Attacks: Forcing Nonce Reuse in WPA2, https://papers.mathyvanhoef.com/ccs2017.pdf
  • CERT CVEs, http://www.kb.cert.org/vuls/id/228519
    • CVE-2017-13077: reinstallation of the pairwise key in the Four-way handshake
    • CVE-2017-13078: reinstallation of the group key in the Four-way handshake
    • CVE-2017-13079: reinstallation of the integrity group key in the Four-way handshake
    • CVE-2017-13080: reinstallation of the group key in the Group Key handshake
    • CVE-2017-13081: reinstallation of the integrity group key in the Group Key handshake
    • CVE-2017-13082: accepting a retransmitted Fast BSS Transition Reassociation Request and reinstalling the pairwise key 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


In early 2017 the researchers were finishing off another security publication when they realised that part of the OpenBSD network code for WiFi that they were discussing had a potential problem. By July 2017 a wide range of systems had been confirmed with this problem, and the CERT/CC co-ordinated a wider notification to OS and device vendors in late August. The public announcement was made on 16 October 2017.

Many vendors have made announcements and released patches already, more will be coming soon. OpenBSD patched early due to their relationship to the original discovery, some other vendors seem to have issued patches already but many important ones are yet to patch.


At the moment I’m getting my information from the CERT/CC and the Bleeping Computer website, but I’ll verify from original sources as soon as I can. https://www.bleepingcomputer.com/news/security/list-of-firmware-and-driver-updates-for-krack-wpa2-vulnerability/

No Patches

If you have a device using WiFi, and there are no patches for it, you should assume that all traffic from that device can be spied on and potentially altered. If you are encrypting your communications with TLS/SSL or something equivalent like OpenSSH, then all you are at risk from is a lack of privacy. However, you might need to consider implementing a VPN if you rely on plaintext or easily spoofed protocols.

Further Questions

If you have any further questions, please get in touch with the Information Security Office through the usual channels.


Microsoft’s iOS and Android Outlook app

Wednesday, February 4th, 2015 | Jim Cheetham | Comments Off on Microsoft’s iOS and Android Outlook app

Microsoft have recently released a new “Outlook” email app on the iOS and Android mobile platforms. This app is a rebrand of the recently-purchased Acompli.

The user interface apparently is quite effective, mixing calendar and priority mail and allowing fast response to messages.

Unfortunately, at this stage in the app’s existence it takes some security shortcuts that are not ideal. All your email is copied into “the cloud” (this is a techno-marketing phrase that simply means “someone else’s computer” – and of course we should assume that “the cloud” will always be in a hostile legal environment, where government agencies from multiple countries will have free access to all your data). Worse, if you are accessing an Exchange service (i.e. University mail) your username and password are also stored in the cloud in order to make this work. The app doesn’t make this clear to users, and for some people that could represent a real problem.

More directly, this cloud-based login also actively violates the security policies that the University sets on Exchange email access. In order to protect University-owned data, devices that connect to Exchange are required to have local security policies like active screen locking, and to respond to remote wipe requests when they are reported stolen/missing. The current Outlook app does not apply these policies to the devices that use it, and although remote wipe might correctly remove data copied into the cloud, it doesn’t remove anything from the missing device. Worse, if you have multiple devices using this app, we can no longer wipe just the missing one; this app services them all from the same connection, and therefore a wipe affects all of them at the same time.

There has been a lot of press about this Outlook app recently – from the usability point of view it’s all positive, and from the security point of view it is all negative. Hopefully Microsoft will be able to put in some new development resources to help address these problems soon.

In the meantime, ISO recommend that you do NOT use this app with University email services.

Android 4 (aka Ice Cream Sandwich) update issues for Nexus S devices

Wednesday, December 21st, 2011 | Gene Teo | Comments Off on Android 4 (aka Ice Cream Sandwich) update issues for Nexus S devices

Recently Google started updating Nexus S smartphones to Android 4.0.

There are reports circulating that Google is occasionally pausing the update process while they monitor progress and feedback. If you are affected by a pause, when you go to Settings > About > System Updates you will be told “Your system is up to date”, even if you’re not on Android 4.0.

If you were able to download the update, click the “Reboot and Install” button, and then see “Your system is up to date” (when again, the update to Android 4.0 hasn’t happened), this is apparently a different problem – see the picture below, and that’s pretty much all the information we have at the moment.

Scrrenshot of the Google Mobile Help Forum post on the Nexus S OTA Update to ICS bug

From the Google Mobile Help Forum

Updating millions of phones is hard, and there are a lot of slightly miffed outraged people out there wanting this update. If you haven’t been able to update, just wait until any bugs have been fixed, and the update process resumes. You will get a more reliable patch as a result.

In the interim, prepare for the update by backing up any important files from the USB storage area of your phone. Just connect your phone to your computer via USB cable – it will show the file storage area just like a USB drive.

To get the best upgrade experience many will factory reset their phones just before or just after the upgrade. You can backup your application data, WiFi passwords, and other settings to Google servers so they can be easily restored after a factory reset. On your Android 2.x phone go to Settings > Privacy > Back up my data

Samsung Galaxy Devices to get Android 4 (aka Ice Cream Sandwich) in Q1 2012

Wednesday, December 21st, 2011 | Gene Teo | Comments Off on Samsung Galaxy Devices to get Android 4 (aka Ice Cream Sandwich) in Q1 2012

Picture of the Samsung GALAXY S 2

The Samsung GALAXY S 2

Update 9 Mar 2012 – it begins!

Hot on the heels of Google releasing an upgrade to Android 4 for the Nexus S, Samsung has announced that their Galaxy product line will get their Ice Cream Sandwich (ICS) upgrade in the first quarter of 2012.

The products that will get the upgrade are:

  • Samsung Galaxy S2 (sometimes written as “Galaxy S II”)
  • Samsung Galaxy S2 LTE
  • Samsung Galaxy Note
  • Samsung Galaxy R
  • Samsung Galaxy Tab 10.1
  • Samsung Galaxy Tab 8.9
  • Samsung Galaxy Tab 7.7
  • Samsung Galaxy Tab 7.0 Plus

Of course, it’s the Galaxy S2 owners who will be most excited – and there are many of them! In New Zealand, Samsung has a 28% share of the smartphone market, compared to 13% for Apple. In contrast, Apple has the tablet market all sewn up with 79% market share, vs. 15% for Android.

Sadly it seems that owners of the still-excellent Galaxy S (the predecessor to the Galaxy S2, released in March 2010) will miss out on an upgrade to Android 4/ICS – it’s not mentioned at all in the announcement.

Android 4 (aka Ice Cream Sandwich) now availible for Nexus S devices

Monday, December 19th, 2011 | Gene Teo | Comments Off on Android 4 (aka Ice Cream Sandwich) now availible for Nexus S devices

Screenshot of the Twitter post with the update news

Over the weeked Google announced via twitter that the next version of Android (version 4) is being deployed to Nexus S smartphones. Android 4.0 (codenamed “Ice Cream Sandwich”) has some design changes, and makes better use of swiping to interact with apps and notifications. See the excellent Wikipedia article for a more comprehensive list of features. Also, there is now built-in support for taking screenshots – press Power and Volume (Down) at the same time to automatically save one.

Reviews of Ice Cream Sandwich are generally very positive. If you have a Nexus S, just go to Settings > About > System Updates to get started. It is about a 130MB download, so make sure you’ve got a good WiFi connection before starting.


NoScript available for Android Firefox

Wednesday, October 19th, 2011 | Jim Cheetham | Comments Off on NoScript available for Android Firefox

The excellent & highly recommended NoScript addon for Firefox has been released on the Android platform (and Maemo, but I’m probably the only person here who has one of those). This addon blocks JavaScript, Java and Flash activity on webpages, giving you a simple way to selectively re-enable trusted providers and restore the full page functionality temporarily if you need it.

https://www.infoworld.com/d/mobile-technology/noscript-security-tool-released-android-maemo-176280 provides a nice writeup; NSA is the distribution point for the add-on itself.