WPA2

(My) BruCON 2018 Notes (Retro Day)

Adrian Citu

Here are my quick notes from the BruCON 2018 conference.This first day was called “Retro Day” because it contained the best (as chosen by peoples) previous talks. All the slides of the conference can be found here.

Advanced WiFi Attacks using Commodity Hardware (by Mathy Vanhoef)

Wifi devices assume  that each device is behaving fairy,share the bandwidth with the other devices for example.

With special hardware it is possible to modify this behavior ; It is possible to do:

  • continous jamming; channel unusable.
  • selective jamming; block specific packets.

Implementing of selfish behavior using cheap devices

Steps to send a frame:
frame1 + SIFS + AIFSN + backoff + frame2

  • SIFS : represents the time to let the hardware process the frame.
  • Backoff :  random amount of time, used to avoid collisions.

Implement the selfish behavior (this was done by modifying the firmware):

  • disable Backoff.
  • reduce AIFSN.

Countermeasures to this problem:

  • DOMINO defense system detects selfish devices

What if are multiple selfish stations ?
in theory : in collision both frames are lost but in reality due to the “capture effect” in a collision the frame with best signal and lowest
bit-rate is decoded (similar to FM radio).

Continuous jamming

how it works:

  • instant transmit:disable carrier sense
  • no interruptions : queue infinite packets

This will
– only first package visible in monitor mode
– other devices are silcenced

What is the impact in practice:
We can jam any device that use the 2.4 and 5 GHz band, not only wifi, but other devices like security cameras.

Selective jammer

Decides based on the header whether the jam the frame
so it should:

  • detect and decode the header.
  • abort receiving current frame.
  • inject dummy packet

The hard part is the first step. This is done by monitoring the (RAM) memory written by the radio chip.

Impact of the attacks on higher layers

Breaking WPA2; this is a shorter version of :KRACKing WPA2 in Practice Using Key Reinstallation Attacks.

Hacking driverless vehicles (by Zoz)

Drivelless vehicles advantages:

  • energy efficiency
  • time efficiency

Main roadblocks:
– shared infrastructure (have to share road/s with card driven by humans)
– acceptance (safety robustness).

Classical failures:

  • RQ-3 DarkStar – self flying drone; it crashed due to cracks into the runway.
  • sandstorm ; self driving car contest: in this case the mismatch between GPS info and other sensor.

Autonomous vehicle logic structure:

Mission task planners
|
Navigation
|
Collision avoidance
|
Control lops

Sensors used by driveless vehicles:

  • active vs passive sensors
  • common sensors:
    • gps
    • lidar
    • cameras
    • wave radar
    • digiwheel encoderes

Sensor attacks

2 kinds:

  • denial
  • spoofing – craft false data

GPS:

  • denial – jamming
  • spoofing – fake GPS satellite signals

LIDAR

  • denial:
    • active overpowering
    • preventing returning signal
  • spoofing
    • can fake road markings invisible to humans
    • can make solid looking objects

Digital compass:

  • extremely difficult to interfere with acoustic attacks.
  • gyroscope vibrates and has a resonance frequency.

Levelling Up Security @ Riot Games (by Mark Hillick)

The talk was structured in 2 parts; what RiotGames do/did to enhance security in 2015 and what they are doing to enhance security in 2018

2015

  • introduced the idea of security champion.
  • introduced the RFC (Review For Commens) document = Technical Design.
    • not an approval process it’s more about receiving advice
    • becomes a standards through adoption.
    • introduction of bug bounty program.

2018

  • security team had doubled in size.
  • sec-ops team and read team are working together.
  • put in place an anti-cheating strategy:
    • prevention
    • detection
    • deterence

Top8 vulnerabilities:

  • improper authentication.
  • open redirect.
  • information disclosure.
  • business error.

Challenges around secrets:

  •  detected an api key from AWS in a commit.
  • how to fix it.
    • provide temporary AWS API token
    • remove the usage of long-lived AWS Api keys.

Social engineering for penetration testers (by Sharon Conheady)

Definition: efforts to influence popular attitudes and social behavior.

Main take away (for 2018); the social engineering (a.k.a SE) is used more and more and actually the techniques it didn’t change too much.

what has changed since 2009 ?
nothing

example of social enginnering through history:

What had changed since 2009 (when the same talk has been given):

  • the scale of the attacks.
  • sophistication
  • more targeted
  • ethical SE is mostly phishing.

Why social engineering (still) works:

  • peoples want to help.
  • greed
  • tendency to trust
  • complacency
  • peoples do not like confrontations.

Stages of an attack

  • target identification
  • reconnaissance
    • passive information gathering
    • physical reconnaissance
    • google map
    • where are the security guards
  • sample scenarios
    • tailgate
  • going in for the attack
    • use your scenario to get in
    • prove you were there
    • have an exit strategy
  • write the report
  • tell the story

The 99c heart surgeon dilemma (by Stefan Friedli)

The presentation was about pen test bad examples and how to make the things better.

It starts with examples of bad pen test:

  • Unclear impact metrics.
  • Accidentally pasting other customer names.
  • Reported false positives.

How to make the things better:

  • Avoid security companies offering bad services. How:
    • Ask about procedures, standards.
    • Ask to talk to the testers
    • Check for community participation
    • Look at sample deliverables
  • How to fix Penetration Testing:
    • Involve more people.
    • Have more conversations.
    • Don’t stop at the report

(My) OWASP Belgium Chapter meeting notes

Adrian Citu

These are my notes of OWASP Belgium Chapter meeting of 19th of March.

KRACKing WPA2 in Practice Using Key Reinstallation Attacks (by Mathy Vanhoef)

This talk subject was about the attack on the WPA2 protocol that was made the (security) headlines last year. The original paper can be found here and the slides can  be found here.

The talk had 4 parts :

  • presentation of the attack.
  • practical impact
  • common misconceptions
  • lesson learned

 Presentation of the attack

The 4-way handshake is used in any WPA2 protected network. His use if for mutual authentication and to negotiate a new pairwise temporal key (PTK).

The messages sent between the client and the access point (AP) are the following ones:

 

The PTK is computed in the following way: PTK = Combine (shared secret, ANonce, SNonce) where ANonce, SNonce are random numbers.

Re-installation attack:

  • the attacker will clone the access point on different channel.
  • the attacker will/can forward or block frames.
  • the first 3 messages are sent back to client and AP.
  • message 4 is not sent to the AP; the attacker block this, and the client install the PTK (as per protocol specification)

  • client can sent encrypted data but the AP will try to recover from this by re-sending message 3.
  • then the client will reinstall the PTK meaning that will reset the nonce used to send encrypted data.

  • the effect of this key re-installation is that the attacker can decrypt the frames sent by the client.

Other types of handshake protocols are vulnerable to this kind of attack:

  • group key handshake.
  • fp handshake.

Practical impact of the attack

The main impact is that the attacker can decrypt the data frames sent by the victim to the AP (access point) and the attacker can replay frames sent to the victim.

  • iOS 10 and Windows, the 4-way handshake is not affected (because they are not following the WPA2 specification), but the group key handshake is affected.
  • Linux and Android 6.0+ that are using the wpa_supplicant 2.4+ version are exposed to install all-zero key vulnerability. The basic explanation of the vulnerability is the following one; the application do not keep the key, the PTK is installed at the kernel level and the application will zeroed the memory buffer that contains the key. But when the key re-installation is triggered, then the all-zero key will be sent to the kernel to be installed.

Countermeasures:

  • AP (access point) can prevent most of the attacks on clients:
    •  Don’t retransmit message 3/4.
    • Don’t retransmit group message 1/2.

Common missconceptions

  • update only the client or AP is sufficient.
    • in fact both vulnerable clients & vulnerable APs must apply patches
  • must be connected to network as attacker.
    • in fact the attacker only need to be nearby victim and network.

Lessons learned

4-way handshake proven secure AND encryption protocol proven secure BUT the combination of both of them was not proven secure.
This proves the limitation of formal proofs so abstract model ≠ real code.

Making the web secure by design (by Glenn Ten Cate and Riccardo Ten Cate)

This talk was about the new version of the OWASP SKF.  I already covered  the SKF in some of my previous tickets (see here and here) so for me was not really a novelty. The main changes that I was able to catch comparing with the previous version :