WPA2 “KRACK”ed: Your wireless may have been compromised

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Introduction

Since 2004, almost all of the Wi-Fi networks in our homes and companies have been stopping the hackers from reading, stealing, or manipulating the data. This was all achieved by the current industry standard, known as WPA2 (Wi-Fi Protected Access 2), which encrypts the data traffic. This WPA2, as it turns out, can be exploited using a cryptographic attack.

 

Release the “Krack”-en!

According to new research from security researcher MathyVanhoef of KU Leuven in Belgium, a zero-day in the cryptographic protocols of WPA2 has left WPA2 vulnerable. An attacker can use the same vulnerability to simulate the attack using Key Reinstallation Attacks (KRACK).

The attacker first obtains a man-in-the-middle (MitM) position between the victim and the real Wi-Fi network (called a channel-based MitM position). However, this MitM position does not enable the attacker to decrypt packets. This position only allows the attacker to reliably delay, block, or replay encrypted packets. So at this point in the attack, he or she cannot yet decrypt packets. Instead, the ability to reliably delay and block packets is used to execute a key reinstallation attack. After performing a key reinstallation attacks, packets can be decrypted.

The direction in which packets can be decrypted (and possibly forged) depends on the handshake being attacked. In simple words, when attacking the 4-way handshake, an attacker can decrypt (and forge) packets sent by the client. When attacking the Fast BSS Transition (FT) handshake, an attacker can decrypt (and forge) packets sent towards the client.

The only limitation for the attacker is that he/she has to be physically present in the range of a target’s Wi-Fi network to carry out the attacks.

 

The KRACK ATTACK Affect

“Any correct implementation of WPA2 is likely affected. To prevent the attack, users must update affected products as soon as security updates become available,” Vanhoef urges. “If your device supports Wi-Fi, it is most likely affected.”

The global use of WPA2 on several millions of Wi-Fi enabled devices has now become problem of colossal scope as this attack works against all modern protected Wi-Fi networks.

Now attackers can steal sensitive data such as credit card numbers, email IDs, passwords, chat messages, emails, and photos using the KRACK techniques.

It is also possible to inject and manipulate data depending on the network configuration. An attacker might be able to inject ransomware or other malware into websites.

 

Addressing the Vulnerability

“[It] now requires testing for this vulnerability within our global certification lab network and has provided a vulnerability detection tool for use by any Wi-Fi Alliance member.” – The Wi-Fi Alliance. 

The Wi-Fi Alliance, an organization which certifies that Wi-Fi devices conform to certain standards of interoperability, has a plan to help remedy the discovered vulnerabilities in WPA2. Summarized, they will:

  1. Require testing for this vulnerability within their global certification lab network.
  2. Provide a vulnerability detection tool for use by any Wi-Fi Alliance member (this tool is based on my own detection tool that determines if a device is vulnerable to some of the discovered key reinstallation attacks).
  3. Broadly communicate details on this vulnerability, including remedies, with device vendors. Additionally, vendors are encouraged to work with their solution providers to rapidly integrate any necessary patches.
  4. Communicate the importance for users to ensure they have installed the latest recommended security updates from device manufacturers.

 

Mitigating KRACK Attack

As of now, one cannot completely prevent the KRACK attacks because the fundamental flaw in the cryptographic protocols, but he/she can soften the attack by following steps:

  1. Make sure that you share sensitive information on sites that use HTTPS encryption.
  2. For large institutions, the key is architecting networks with multiple layers of protection, so data security doesn’t hinge on any one standard.
  3. The networks should be segmented, so compromising one component doesn’t give attackers access to everything.
  4. Implementing of wireless isolation will prevent one Wi-Fi client from talking to another.

It does highlight that enterprise networks need to be secure even if they have WPA2-enterprise protection.

Action points for enterprise customers

  1. Access points as such do not need to be patched. Though it appears that Aruba and other AP vendors have released patches
  2. Endpoints do need to be patched. The researcher states that nearly 41% of Android devices were found vulnerable.
  3. Windows and iOS devices aren’t vulnerable to the sniffing attacks.

 

Overall

In my opinion, let us not overhype the issue for the following reason:

  1. This vulnerability comes into play only on an unpatched device that connects over WPA2.
  2. Even though this is the large majority of Wi-Fi connected devices, the vulnerability doesn’t reveal the WPA2 key. It only allows parts of the communication to be sniffed.
  3. Since most Wi-Fi communication is likely to be HTTPS and SMTP-S, the attacker would end up sniffing only TLS encrypted traffic.
  4. An attack or exploit has not yet been seen in the wild. Though this may change shortly.
  5. Windows devices aren’t really affected.
  6. For affected Android devices, patches have already been released.

If I get any further updates that change my stance, I’ll update, but at this stage no need to panic.

Also, for further and fairly accurate updates you may want to follow the researcher’s Twitter handle: MathyVanhoef (@vanhoefm)

 

Got comments? Did I miss something? Comment below…

It’s time for you to conduct Wireless Risk Assessment to avoid any attacks. Drop me a line and I can help you along.

Kumar Jishu is a Cybersecurity Analyst working for VISTA InfoSec, a PCI QSA company providing vendor neutral consulting services in the areas of Information Risk Compliance and Infrastructure Advisory Services. For more information, email me at kumar.jishu@vistainfosec.com. My LinkedIn profile can be viewed at www.linkedin.com/in/kumarjishu/

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