Is there a way to change the subject of the certificate Fiddler uses when re-encrypting https traffic? Currently, it says CN=DO_NOT_TRUST_FiddlerRoot. I have a program that reads the subject and I'd like to run some tests where I customize the CN, O, and OU of the subject.
Any suggestions?
Fiddler can be reconfigured to use a custom certificate generator:
Fiddler uses a pluggable architecture for certificate generation.
Developers provide their own certificate-related logic by implementing
the ICertificateProvider3 interface on an assembly specified by the
fiddler.certmaker.assembly preference, which defaults to
"certmaker.dll". [source]
Therefore with some .Net development you could develop an Fiddler add-on that implements the ICertificateProvider3 and generates certificates exactly the way you need it. If the number of domains is limited you could even use pre-generated certificates which would simplify the "generator" logic.
Related
How do browsers like Chrome check SSL Certificate?
IS there any online databases or websites that they use?
What steps are taken by browsers to validate a SSL certificate?
Am I able to do it manually without using browser?
How do browsers like Chrome check SSL Certificate?
The certificate and chain is send by the server during the SSL handshake. The browser will create the trust chain based on the certificate issuer, provided chain certificates and the local root certificates. It will check expiration and purpose of the certificate and also check the subject alternative names (and maybe subject too) to make sure that the certificate is actually issued for the domain in the URL. It might also do some checks for certificate revocation.
For details see SSL Certificate framework 101: How does the browser actually verify the validity of a given server certificate? and How Do Browsers Handle Revoked SSL/TLS Certificates?.
I there any online database or websites that they use?
Not really. The necessary trust store is local. They might check revocation though against some online resource. See Is Certificate validation done completely local?.
Am I able to do it manually without using browser?
Sure, what the browser does could in theory be replicated manually. You can for example access the site and get the leaf and intermediate certificates with openssl s_client -showcerts .... You can then use openssl verify to verify the certificate chain, see also Verify a certificate chain using openssl verify. Then you need to look at the leaf certificate with openssl x509 -text ... to check purpose, expiration and the subject. Revocation is tricky but could be done with the help of openssl crl and openssl ocsp, although this does not really reflect what browsers do.
The official algorithm for validating any SSL/TLS certificate is defined by PKIX as modified by OCSP. For TLS nowadays the OCSP token is often transported by 'stapling' in the TLS handshake instead of by a separate connection, which requires several other RFCs, but that only affects transport, not the actual validation by the relier. For HTTPS specifically, the client must also check server identity aka 'hostname' as defined by rfc2818.
In practice, browsers may vary some. Chrome mostly uses a google-determined scheme to 'push' revocation data they select, but this has changed from time to time. Firefox, last I heard, used their own 'one-CRL' scheme. Also, although the standard and traditional practice was to check hostname against SAN if present and otherwise fall back to Subject.CN, Chrome since a few years ago requires SAN and never uses CN; you can find dozens of Qs on several stacks about "my selfsigned or otherwise DIY cert not from a real CA stopped working on Chrome".
If by 'do it manually' you really mean manually, that will be a lot of work. If you mean with tools other than a browser offline, somewhat easier; OpenSSL (if installed) can do most of this, although you need more options than shown in Steffen's link to get it right.
If you mean with tools other than a browser online, absolutely. The WWW has become extremely popular in recent decades, and there are zillions of programs and libraries for accessing it, nearly all of them including HTTPS (although two decades ago that was less common), which includes validating the certificate -- at least by default; many have options to disable, bypass, or override validation. There are standalone tools like curl and wget -- or openssl s_client can do the SSL/TLS and certificate part without doing HTTP on top. There are innumerable libraries and middlewares like ssl in python (or requests using it), tls in nodejs, (older) HttpsURLConnection and (newer) java.net.http in Java as well as third-parties like Apache HttpComponents; I'm sure there are counterparts for perl and dotnet although I'm not familiar with them. As well as powershell, which is fuzzy on the program/library distinction.
I'm writing a utility Mac OS X app that basically acts as a web server accepting incoming HTTP requests (think of it as a mock REST API server). I want to be able to support HTTPS, but ideally I'd like to remove the requirement for my users to have to purchase their own SSL certificates.
I've been thinking a little on how I might achieve this. Let's say I register a domain called myapp.com. I then purchase an SSL cert for myserver.myapp.com that is signed by a registered CA. I ship my app with those SSL cert details embedded within it. All my users have to do is update their /etc/hosts file to point myserver.myapp.com to whatever IP address my app is installed and running on.
In fact, by far, the most common scenario would be my app running on the same machine as the client, so I'm considering updating the main DNS entry for myserver.myapp.com to point to 127.0.0.1, and most users wouldn't have to change anything.
So, that's the basic theory. What have I missed that would make this an unworkable plan? A couple of things that have crossed my mind:
I could use a self-signed cert. However, many SSL clients barf (or throw up warnings) if the cert doesn't have a valid CA chain. I'm happy to pay the money for a real cert to alleviate this inconvenience for my users.
I would be embedding the private key for my SSL cert into my app. In theory, someone could extract that and use it to impersonate my app. I guess my reaction is "so what?" My app is a small productivity app, it isn't an e-commerce site. It doesn't collect sensitive info. It literally just simulates web server responses so devs can test their apps.
Any advice/feedback would be greatly appreciated. Thanks.
This won't work - but for nontechnical reasons.
Distributing an SSL certificate to your users along with its associated key will violate the issuance terms of your SSL certificate provider, and they will revoke the certificate when they discover what you have done. (This happened, for example, when Pivotal tried to offer SSL service for developers through sslip.io.) This will, of course, cause your application to stop working.
If your users have administrative access to their machines, they can create and trust their own self-signed CA using Keychain Access. Once they have done so, they could create a certificate (again, using Keychain Access) and insert that into your application to enable SSL.
As said in the other answer you can't ship the same certificate for everybody. What you could do is generate different for everybody:
The application ask them the domain name they want to use (a domain they must own, like myapp.example.com)
The application use the ACME protocol to get automatically a trusted certificate from let's encrypt
Note: you can provide them subdomains of a domain you control (like [clientid].yourappname.yourdomain.com) ONLY of you can register yourappname.yourdomain.com in the public suffix list (because let's encrypt have rate limits)
I've been struggling recently with using the standalone DartVM and SSL as a client. I'm of the understanding that Dart uses Mozilla NSS to manage the certificates. What I'm having a problem wit, is that on Windows, for example, there exists no binaries that I can find (other than third parties compiling the Mozilla source and uploading to mega or similar, which is pretty alarming if you ask me) released for the Windows platform. Compiling this C++ code is not a trivial task. I've not the resources to do so on my own under the Windows platform. This is why I write Dart (or other high level languages) in the first place.
Despite that, the error message I get when attempting to connect securely and being presented with a self-signed (or rather more technically correct, untrusted authority) certificate, is that the OS itself doesn't trust the certificate. On Windows, this is not the case. The certificate in question I'm using is a CA root certificate of my generating, with proper authority/signing chain, installed into Windows trusted roots manually. Both Chrome and Internet Explorer (of which use the Windows underlying certificate store) trust my certificate(s) without any warnings after having done this. So if the DartVM is not using the "OS" to validate a certificate upon handshake, then that message is very uninformative/misleading.
What can be done to overcome this outside of compiling NSS and trying to figure out just how to import my certificates by way of over-complicated and under-documented steps? Is there not a parameter that one could specify when initiating a secure connection to ignore SSL errors of this nature?
My web server forces the use of HTTPS so dropping back to plain HTTP would
not be an option for me. I also don't want to trust and much less want to pay a third party for my certificates of which are pretty much only used internally, which is why I generated a wildcard certificate under my own root CA in the first place. Paying for a wildcard certificate, for multiple domains, that aren't always necessarily exposed to the public or meant for public use is a bit astronomically priced and completely out of the question.
I've been playing with the twitter API for an iPhone test application, and I've missed the ability to proxy the requests I did to the twitter API with a software like Charles (http://www.charlesproxy.com/). Even though it has a SSL Proxying feature, twitter seems to not like the fact that there's a different certificate in the middle signing the requests.
Is there any way to do this? I'd be very useful to be able to see the requests and the way Charles formats the JSON responses, etc...
Twitter can't know that there is a man in the middle. I've not used Charles, but I've used Fiddler2. Try that one.
http://www.charlesproxy.com/documentation/proxying/ssl-proxying/
http://www.fiddler2.com/fiddler/help/httpsdecryption.asp
Decrypting HTTPS works by the proxy making its own certificate, and giving it to the browser. The browser will notice it connects with a bad certificate and give a warning, but the server (Twitter) will just see the proxy as another browser. The proxy-server connection uses Twitter's certificate, so it's still secure.
Perhaps this is your problem:
Q: Can Fiddler intercept traffic from Apple iOS devices like
iPad/iPhone/iPod Touch and Android devices? A: Yes, but these devices
may not be compatible with the default certificates Fiddler generates.
To resolve the incompatibility, you may replace Fiddler's default
certificate generator with one that generates certificates containing
flags (e.g. AKID, SKID) that are compatible with these platforms.
Simply download and install the new Certificate Maker and restart
Fiddler.
Is it different from any other certificate I can generate via makecert or buy from some authority?
As mentioned by Mile L and Boot to the Head the Extended Key Usage is what determines the purpose that the key can be used for.
Most commercial certificate authorities (Verisign et al) issue certificates for single purposes, or for as few as possible.
They use this narrowing of the puropse to carve out different markets for the certificates and then price them accordingly.
You see them selling different Object Signing certs for Windows Assemblies / Java / Office / Adobe Air etc when (in most cases) the resulting certificate is the same.
For example the Comodo codesigning cert issued here can sign Java applets, WebStart applications, Firefox extensions and even Windows assemblies.
The certificate that's used to sign software is the same certificate that would be used to sign any document. What's different about signing software is where the signature finally resides. In a typical document signing, the signature just gets appended to the original document. You cannot append a signature to most types of software for obvious reasons (some interpreted languages would allow this, but I don't know if it's done in practice).
The solutions to the signature problem vary based on the execution environment. For an executable binary, the signature is often stored in a separate file. In Java you can have a signature embedded in an executable JAR file.
Microsoft has a good reference for an introduction to the signing process.
It depends on what you are doing with it. If you want the certificate to be accepted by a browser in an SSL communication, then it must have a root certificate installed in the browser. The certificates generated by authorities already have their root certs installed in browsers.
If you are using the cert just to sign an assembly, then you don't need it. It depends on who is checking the cert and whether they care if the root is a known authority.
More here:
http://en.wikipedia.org/wiki/Root_certificate
To my knowledge, certificates have a "key usage" attribute that describes what uses the cert is intended for: SSL server, code signing, e-mail signing, etc. So I think it's up to the OS, or web browser, or e-mail client, to check these bits.
When a cert is called into action, the role it purports to perform is as important as identification. It's not just about identity, but also about role authorization. An email protection cert should not be able to perform server authentication. Security concerns dictate a necessary restriction in the power given through a single certificate. The underlying API should enforce the correct usage, be it through the OS or an abstraction such as the .NET Framework.
There are different certificate types because there are very different roles in authentication and authorization that would need them. Allowing different certificate types and hierarchies allow for a model of certificate chains, as found in the "Certification Path" on a certificate. A Server Authentication cert will need to have a top-level CA cert somewhere in the trusted root certificates... or be a part of a family tree of certs which ultimately does. 3rd party Certificate Authorities, I'm sure, price them on a scale of functionality and trust.
Boot To The Head is right... there is an Enhanced Key Usage attribute which provides a description of what the cert claims the role to be (e.g. Server Authentication; or in the case of my CA's cert: Digital Signature, Certificate Signing, Off-line CRL Signing, CRL Signing). Look at the details in a certificate's properties and you'll find it.
I'd also add that a .NET assembly has to be strongly named (which requires it to be signed) in order to be added to the GAC.
There are different types of certs... from the CA that is bundled in Win 2003 server, you can request:
Client authentication
Email protection
Server authentication
Code signing
Time stamp signing
IPSec
Other