Pinning Down The IoT [REPACK]
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Certificate pinning restricts which certificates are considered valid for a particular website, limiting risk. Instead of allowing any trusted certificate to be used, operators \"pin\" the certificate authority (CA) issuer(s), public keys or even end-entity certificates of their choice. Clients connecting to that server will treat all other certificates as invalid and refuse to make an HTTPS connection.
Pinning allows websites to control the risk of misissuance, CA compromise, or man-in-the-middle attacks. Pinning takes multiple forms depending on the use case - I can pin my certificate as the only one in my client trust store or write the public key hash into my code so only my key is trusted. When pinning started becoming popular, the hope was that these extra layers of complexity made it harder for bad actors to use certificates in attacks or spoofs.
Google was one of the first to use pinning in 2011, when they pinned the issuing CAs for their main websites in the Chrome browser. When Chrome connected to google.com, it already knew which CAs to accept. If a certificate from any other CA was presented, the connection would be blocked. This meant that if an attacker managed to fool any other trusted CA into giving them a certificate for google.com, it would still be blocked by Chrome.
Meanwhile, certificate pinning was also introduced in apps, IoT devices, and other software. Using similar methods an app could pin a certificate, and the app would then refuse any connections to the server if they were not using that certificate, protecting users from any man-in-the-middle attack.
Pinning, especially with HPKP, was extremely risky and error prone. If you configured your pinning settings incorrectly, you could block access to your own website or break connectivity in your application, with limited options for recourse. Here are just a few ways pinning can cause such harm.
As a result of these problems and the difficulties of implementing pinning safely and robustly, there were more cases of sites being harmed by pinning than protected. These are just a few of the issues with pinning which led Google and Firefox to remove HPKP support just a couple years after it was introduced.
The biggest problem with pinning is that you lose the ability to respond to certificate issues. If you need to change keys, certificates, issuers, or your CA vendor, for any reason, you must fix your client, browser, code, IoT device, etc. - sometimes on a short schedule. If you are committed to supporting an application version for years and it contains a pinned certificate, how can you be sure the certificate will remain valid for the entire lifetime of your application Pinning is especially problematic with publicly trusted TLS certificates because they must adhere to ever-evolving rules, decreasing maximum lifetimes and other surprises.
Luckily, HPKP is a thing of the past, and DigiCert has not been a big proponent of other types of public key pinning. DigiCert recommends you do not use pinning; the complexities and consequences outweigh the benefits.
While we haven't recommended or instructed users to implement pinning in recent years, it is still possible to set up pinning on your own. This week, DigiCert is making a change to our CA hierarchy. We will start replacing our public TLS-issuing intermediate CAs (ICAs) with shorter versions, updated every six months. Of course, the validity periods of the intermediates will be long enough to exceed all the one- and two-year certificates issued during the six months the ICAs are used. Shorter ICA lifetimes will disincentivize pinning them since they will be changing more frequently.
Beyond helping put pinning behind us all, shortening ICA lifetimes will have other benefits. It will group certificates into smaller buckets so changes to one set of certificates issued under one CA will not always affect others. If an ICA must be deprecated, it will only affect the certificates issued for the six months that CA was actively issuing, and only the specific types of certificates that were allowed under that CA.
Keep in mind thatRMS is only specific to random jitter, where one needs to divide therandom jitter requirement by the BER multiplier to knock that down tothe corresponding RMS random jitter UI. For random jitter, you can use aPN plot with spurs turned off and then integrate to arrive at an RMSphase jitter value. But, when we take a PN plot with spurs turned on tocapture the deterministic jitter and then integrate per the mask, thenthe corresponding value is no longer RMS and is instead total phasejitter.
Instagram introduced Reels in 2020 to counter TikTok in the same manner as when it launched Stories to strike down then-rival Snapchat in 2016. Although TikTok only grew more popular, the hype surrounding Reels prior to its launch increased the number of users by 4.34% and it has been a stiff battle between the two platforms since.
I'm just one of many members of a group in this area at Cornell. My closest colleagues and co-leaders of the group are Robbert van Renesse and Hakim Weatherspoon. But the systems group is very strong and broad right now, and the three of us have great relationships and collaborations with many other systems faculty here at Cornell (both in the systems area within CS, but also folks in ECE where we have great ties, MAE, IS, and down in New York City, where a few faculty are members of our fast-growing New York City Technology \"outpost\" on Roosveldt Island.
Note: if you allow list a certificate or public key for a different host(for example, to accommodate an interception proxy), you are no longerpinning the expected certificates and keys for the host. Security andintegrity on the channel could suffer, and it surely breaks end-to-endsecurity expectations of users and organizations.
There is a downside to pinning a certificate. If the site rotates itscertificate on a regular basis, then your application would need to beupdated regularly. For example, Google rotates its certificates, so youwill need to update your application about once a month (if it dependedon Google services). Even though Google rotates its certificates, theunderlying public keys (within the certificate) remain static.
Public key pinning is more flexible but a little trickier due to the extra stepsnecessary to extract the public key from a certificate. As with a certificate,the program checks the extracted public key with its embedded copy of the publickey.
If devices running a version of Android that is earlier than N need tobe supported, a backport of the Network Security Configuration pinningfunctionality is available via the TrustKit Android library.
Note that using ServicePointManager.ServerCertificateValidationCallback affectsserver certificate validation for all requests requiring validation from the AppDomain. It is therefore advisable to check that the sender represents a requestto the authority to which to apply certificate pinning, as the example above demonstrates.
Though OpenSSL performs the X509 checks, you must fail the connectionand tear down the socket on error. By design, a server that does notsupply a certificate will result in X509_V_OK with a NULLcertificate. To check the result of the customary verification: (1) youmust call SSL_get_verify_result and verify the return code isX509_V_OK; and (2) you must call SSL_get_peer_certificate and verifythe certificate is non-NULL.
Ephemeral keys do not affect pinning because the Ephemeral key isdelivered in a separate ServerKeyExchange message. In addition, theephemeral key is a key and not a certificate, so it does not change theconstruction of the certificate chain. That is, the certificate ofinterest will still be located at certificates.
A client can suggest a list of higher cipher suites to use during ClientHello. However, some of them might not be supported by IoT Hub (for example, ECDHE-ECDSA-AES256-GCM-SHA384). In this case, IoT Hub will try to follow the preference of the client, but eventually negotiate down the cipher suite with ServerHello.
Certificate pinning and filtering of the TLS server certificates (aka leaf certificates) and intermediate certificates associated with IoT Hub endpoints is strongly discouraged as Microsoft frequently rolls these certificates with little or no notice. If you must, only pin the root certificates as described in this Azure IoT blog post.
Pinning down a definition for something as diverse as smart technology can be quite an arduous task given that the field of smart technology is developing at a relentless pace, making innovations outdated almost as quickly as they arrive.
Industry 4.0 carries a multitude of implications. From being overused in marketing tactics to being portrayed as a mechanistic threat to factory workers, pinning down a definition can be tough. But at its core, it simply refers to the increasing automation of industry through information technology.
Two recent articles stated that IoT itself is so vast and complex that pinning down a single skill is certainly not easy (zdnet) and Computer Business Reviews listed five skills necessary to succeed in IoT development:
With certificate pinning, the backend server is associated with an X.509 certificate or public key. Instead of accepting any certificate signed by a trusted certificate authority (as we saw above), the application is designed to accept only specific trusted certificates.
After pinning the server certificate or public key, the mobile application will only connect to the known server. The application will not trust custom certificates and, by default, will not allow proxy tools (burp, MITM Proxy, etc.) to intercept the traffic.
Essentially, if you use certificate pinning, you are removing the trust from external certificate authorities, thus reducing the overall attack service and adding a layer of security to your mobile application.
How many applications are doing this While many applications still do