More Side-Channel Attacks

Side channel attacks have always been there, but with Spectre and Meltdown we reached a new level of complexity, danger and pervasiveness. Somehow one of the main ingredients of this family of attacks is to measure the time (or time difference) it takes to process/compute some data and from this to infer information about the data itself. In the 3 years since the announcement of Spectre and Meltdown, a lot of research has been done on this area to find more hardware components suitable to time measurements which can be exploited, to improve the efficiency of the attacks (for which Machine Learning is of great help), and to understand if this type of attacks can become a real everyday threat for everyone. There are recent results in all directions: “Lord of the Ring(s): Side Channel Attacks on the CPU On-Chip Ring Interconnect Are Practical” exploits the contention on the CPU ring interconnect (see here and here for details and the research paper), whereas Google Security made further progress in implementing Spectre against the Chrome Browser using Javascript (here the blog announcement) and other researchers have discovered a way of performing a side channel attack in a Web Browser with Javascript completely disabled (see here and here for details and the research paper) which can be used as an alternative way of to tracking users online. In particular the latter result is worrisome: it seems that the possibility of being subject to this kind of attacks in everyday life, that is browsing in internet on websites, is getting closer.

Online Tracking and the End of Third Party Cookies

Third party cookies as those cookies that a browser sends to a different website that the one we are visiting. This functionality is used and too often abused for marketing purposes and to track users’ Web navigation. Indeed the latest announcements by browser makers indicate that in one year most browsers will not allow anymore any third party cookie. 

But there is a nice little trick to run around this restriction. Suppose one is visiting the company.com website. Cookies for the websites in the company.com domain and any subdomain like shop.company.com are not third party, whereas relatively to the company.com domain, cookies for websites in the tracker.com domain are third party. Now the idea is very simple: what if there is a domain tracker.company.com which points to the tracker.com website? Cookies for tracker.company.com are not third party, so they are allowed. And this can be done quite easily with the appropriate DNS configuration. The principal DNS record is an A (for Address) type record which maps a domain name to an IP address. But very common is also the CNAME (Canonical Name) record which maps a domain name to another domain name (that is an alias), like tracker.company.com mapped to tracker.com. So the browser sees tracker.company.com (first party), but the cookie ends up in tracker.com (third party). As simple as that. 

Third party cookies are mostly used for advertisement purposes: in practice in the website one puts some code from the advertisement company which displays advertisements, counts views and tracks viewers. With CNAME-cloaked tracking the owner of the website not only has to install the code for displaying the advertisements, but also to insert in the DNS the CNAME record to the advertisement website.

Third party cookies have not disappeared yet, and the competition on CNAME-cloaked tracking has already started: how can browsers and AD-blocker extensions block these disguised third party cookies? And how can advertisement companies can continue to track users’ Web navigation?

PS. A non technical comment: nothing is really for free in life, free resources on Internet must be payed by someone, and a free website is often payed by advertisements. The important point is to find the right balance between price and hidden costs (including our personal information).

Hardware Vulnerability of Some FIDO U2F Keys

Hardware Security Keys, like Google Titan Key or Yubico YubiKey, implementing the FIDO U2F protocol, provide what is consider possibly the most secure 2nd Factor Authentication (2FA) measure. Indeed the private key is protected in Hardware and should be impossible to copy, so that only the physical possession of the hardware token provides the authentication.

But a recent research (see here for the research paper, and here and here for some comments) shows that a class of chip (the NXP A700X) is vulnerable (CVE-2021-3011) to a physical hardware attack which allows to extract the private key from the chip itself, and then to clone the security key. To fully succeed, the attack requires to know the credential of the service(s) for which the security key works as 2FA and the physical availability of key itself for at least 10 hours. Then the security key is dismounted and the secret key is obtained by measuring the electromagnetic radiations emitted by the key during ECDSA signatures. Finally a new security key can be cloned with the stolen secret key.

From a theoretical point of view, this vulnerability violates the fundamental requirement of an hardware security key, that is that the private key cannot be extracted from the hardware in any way. But it should also be noted that the FIDO U2F protocol has some countermeasures which can be useful to mitigate this vulnerability, like the presence of a counter of the authentications done between a security key and a server so that a server can check if the security key is sending the correct next sequence number which would be different from the one provided by the cloned security key.

On practical terms, it all depends on the risks associated with the use of the security key and the possibility that someone will borrow your security key for at least 10 hours without anybody noticing it.  If this constitutes a real risk, then check if your security key is impacted by this vulnerability and in case it is, change it. Otherwise if this attack scenario is not a major threat, it should be reasonably safe to continue to use even vulnerable security keys for a little while, while keeping up to date with possible new developments or information from the security keys manufacturers. Even in this case, vulnerable security keys should anyway be changed as soon as convenient.

 

News on Fully Homomorphic Encryption

Fully homomorphic encryption (FHE) would drastically improve the security of sensitive computations and in general of using Cloud and third party resources, by allowing to perform computations directly on encrypted data without the need to know the decryption key. 

But as of today, fully homomorphic encryption is extremely inefficient making it impractical for general use. Still development is continuing and new results are achieved. For example recently IBM announced an Homomorphic Encryption Service, which is probably more like an online demo but the purpose seems to be to simplify the path for an early adoption by specially interested parties. But IBM is not alone and, among others, Google and Microsoft are developing Open Source libraries which can be used by a developer expert in cryptography to build for example end-to-end encrypted computation services where the users never need to share their keys with the service.

ATP Attacks and Single Point of Failure

We are all following the development of the “SolarWinds incident” but one comment comes to my mind (see also this Advisory from NSA).

There is a very difficult trade-off between management of IT in general but also of IT security, and security itself. To manage IT, from network to servers to services, and IT security it is definitively more effective to be able to do it from a central point, adopting a single strategy to manage and control everything in the same way and at the same time (the “holistic” approach). This means to have a single/central console/point to manage and control all of our IT systems and services, a single point in which to authenticate all users (eg. Federated Single Sign-On) etc. This approach is becoming more and more a requirement as we are moving  towards a service-based IT where services can be anywhere in Internet, access requires a Zero Trust approach, and security is applied at a very granular level to all systems and services.

Doing this we can vastly improve the security of each single system or service, and gives the possibility to monitor each single access or transaction. But in doing so we concentrate in single points activities crucial in particular for security: What can happen to systems and services if the central management console is taken over? What can happen to systems and services if the central authentication service is infiltrated?   

Malware, Ransomware & co.

These days, apart from reading about major incidents like the SolarWinds one, I keep hearing directly from people I know about malware incidents, ransomware incidents and so on. My personal statistics have never been so high. I do not know if this is a personal unlucky end of an unlucky year or a very bad end of an already bad year. I wish to everybody a pandemic-free (in all senses) 2021!  

Mixed Results on AI/ML from Google

Artificial Intelligence, or better Machine Learning, is increasingly becoming part of everyday IT, but it is still unclear (at least to me) which are its real potentials, limits, risks etc.

For example, very recently there have been 2 somehow contradictory news from Google/Alphabet funded research in AI/ML:

  • the paper “Underspecification Presents Challenges for Credibility in Modern Machine Learning” (here the full paper) studies some possible reasons why “ML models often exhibit unexpectedly poor behaviour when they are deployed in real-world domains“, but it is unclear (at least to me) how much these Challenges can be overcome;
  • CASP has announced (here the announcement) that DeepMind AlphaFold has practically solved the problem of predicting how proteins fold, which is fundamental to find cures to almost all diseases, including cancer, dementia and even infectious diseases such as COVID-19.

Thoughts on Blue/Red/Purple Teams and defending from Targeted Attacks

Defending against Targeted Attacks (and even more against Advanced Persistent Threats, APT) is difficult and usually quite expensive. 

We all know the basis of IT security, from cybersecurity awareness and training to anti-malware, firewall and network segmentation, hardening and patching, monitoring and vulnerability assessments / penetration tests (VA/PT),  third-party cybersecurity contract clauses, etc.

But this is not enough. We need also Single-Sign-On (SSO, or even Federated Authentication) and Multi-Factor-Authentication (MFA), Zero Trust architectures, tracing of all local, remote and mobile activities (networks and hosts), SIEM data collection/management and SOC analysis, a cybersecurity Incident Team and an Incident Response plan.

But to defend against Targeted Attacks we need to go another step further. We have designed and implemented all security measures we could think of, but are they enough? Did we forget something? For sure we are ready against an everyday malware attack, but a Targeted Attack which could take months to study us and be implemented?

To answer this question it seems that the only possibility is to think and act as the attacker and look at our IT environment from this point of view. It is here that Blue, Red and Purple teams enter into play as they play the roles of attackers and defenders on our IT environment to test our cybersecurity standing to its limits. They will find holes and access paths we did not think about or even believe possible, but also smarter ways to defend ourselves.

But … what about a Risk Based approach to Security?

In other words, how much is it going to cost us?

Can we afford it?

Finally, is it worth going “all out” or, by accepting some risks, we can continue to do what we have been doing all along in cyber/IT-security? And in this case, how do we evaluate these “Risks” we need to accept?

PS. The last is partly a rhetorical question on my side.

Another Example of how Implementing Cryptography is Tricky (and a Score 10 CVE)

It has recently been published the description of Zerologon, CVE-2020-1472 (see here for a summary and here for the technical paper), and do not worry since the bug has already been patched by Microsoft in August (see here). 

The bug allows anyone who can connect in TCP/RPC/Netlogon to an unpatched Active Directory domain controller to become a domain administrator, nothing else needed. The cause of this bug is a minor glitch in the implementation of the cryptographic algorithm AES-CFB8: the Initialisation Vector has been kept fixed at zero instead to be unique and randomly generated (more details are provided in the technical paper mentioned above).