I would like to use google certificate transparency API to check the malicious SSL certificates(if any) of my domain. I am able to get all the certificates but how do i check whether the certificate is legitimate or not.
I had found this repository(https://github.com/ProtonMail/ct-monitor) but this simply searches certificates and stores it . What is the use of storing these certificates unless we validate the certificates first.
Can any one suggest me how do i get to know the malicious SSL certificates using this google certificate transparency api.
Certificate Transparency logs are, as explained on the CT site:
simple network services that maintain cryptographically assured,
publicly auditable, append-only records of certificates. Anyone can
submit certificates to a log, although certificate authorities will
likely be the foremost submitters.
The logging of the certificates in this fashion allows for interested parties (e.g. domain owners) to monitor these logs for malicious/erroneous
entries.
But a certificate being logged in a CT log doesn't mean it isn't a bad certificate. As explained on the CT site:
Certificate Transparency relies on existing mitigation mechanisms to
address harmful certificates and CAs--for example, certificate
revocation--the shortened detection time will speed up the overall
mitigation process when harmful certificates or CAs are discovered.
So CT API won't help you in working out whether a certificate is malicious - you need to check using other methods such as checking of certificate revocation lists (CRLs) or by using the Online Certificate Status Protocol (OCSP). See this related question on how to check certs. There are sites that allow for checking of certificates e.g. revocationcheck.com. Modern browsers seem to be converging on the use of compressed lists of CRLs - Mozilla's now using CRLite, whilst Chrome uses CRLSets.
The CT API allows you verify that a certificate has been logged in the CT logs which means that domain owners can monitor them and promptly insert any malicious/erroneous certificates into the relevant CRLs so they won't be used any longer.
Related
I have to develop a web application that is both secured over https and uses client authentication certificates. The clients are connecting via invitation, thus it is not intended for users stumbling upon this application by googling around.
The ideal would be to get an intermediate CA certificate form a public root authority and sign both the ssl certificate and use it to issue client authentication certificates. I think that won't work, as simply put I will never qualify for such an intermediate CA (as far as I know, but maybe I am wrong with that).
Second guess: create own Root CA, an intermediate CA and use them. Because of what I wrote about the users, I can embed the necessary certificate chain in the issued certificates. This technically works.
What I would prefer is to get an ssl certificate from public authority and to use my own chain to issue authentication certificates and verify the users. According to this it is possible. But I haven't found anything about how to configure IIS for example (or Kestrel) to request client certificates issued by a specific CA, even less some standard specification where this flow is described.
I am currently struggling with an issue which I am now led to believe is being caused by IIS.
I am currently testing a self signed PKI setup with a Root CA (MyNewCA), two signed Client Certificates (certificate1, certificate2) and a Revocation list (revocationlist.crl) that is also signed by the CA.
I have added certificate1 to the revocation list and published it to a http port 80 site that exists on our network. I have then created a fake site (testsite) that is secured via a TLS certificate.
From a client machine, I have run the CertUtil commands on both certificate1 and certificate2 and these commands correctly access the http crl site, and recognise that certificate1 is revoked, and certificate2 is a legitimate non revoked certificate.
However, when I connect to the testsite via a client browser, and supply the invalid certificate - IIS still serves me the page instead of giving me a 403.13 error.
I have done a ton of reading, and it seems that at times there are CRL caching issues, however the first revocation list that I published had certificate1's serial number in it, and hence even a cached version will contain that revoked cert.
I have changed the CertCheckMode in RegEdit on the IIS server to the value 4 in an attempt to force IIS to fetch the latest crl on EVERY request, but even that setting is still allowing the revoked certificate to be served to the client.
The CRL itself has;
Effective date of 19th January 2016
Next update of 20th January 2017
I can provide the certutil output if it is useful, or any other log data that would help in pinpointing the problem.
I ran Fiddler on my client machine and verified that the crl was fetched from the Http site.
If anyone can provide any insight into this issue I would greatly appreciate it.
Thanks,
It is expected behavior. IIS do not prevent access to SSL sites even if there are revocation issues with the SSL cert. It is up to client what to do with the information it receives from the server. It is up to client to perform (or to not perform) revocation checking and to make decision about further steps.
In addition, make sure if client's cache has the most recent CRL.
I want to support HTTPS in my web application. Since the certificates from Verisign are costly, I decided to use openssl for generating certificate. Here is the link I referred https://community.jboss.org/wiki/JBossAS7ConfiguringSSLOnJBossWeb
When I tried to access the application in browser I got the error "The site's security certificate is not trusted". Here is the screenshot,
Please let me know how I can solve this error? Is it possible to use openssl in production?
The issue is that your self signed certificate is not 'trusted' by the browser. It does not recognise it as signed by one of the certificate authorities it trust.
You have two options - tell the browser it can trust the certificate or tell the browser that it can trust the entity which issued it (meaning that if you use the same certificate to sign other certificates; that those also get trusted).
See http://googlechrometutorial.com/google-chrome-advanced-settings/Google-chrome-ssl-settings.html for more information. Once you are in 'Manage certificates' you can import your own ones.
Every browser, every users, will have to go through those steps. So that is practical logistical limit on how much 'production' you can run with this.
Do check out the various 'free' certificates; they are very low cost.
MAC SOLUTION: The best way that I've found for manually trusting specific site certificates is to use Safari. See, when you manually trust a certificate in Safari, it requires you to enter your OS X account password. Safari does this because it stores the certificate details in Keychain Access, a system application that manages all vital data you store on your computer.
This is significant because Chrome also communicates with Keychain Access. Once the program has a record of the certificate being trusted by Safari, Chrome will also trust the certificate. You may have to restart the Chrome browser after activating the certificate in Safari to get this to work correctly.
Happy browsing!
I have a mobile app that will be communicating with my webserver over https. My question is, do I even need to worry about installing a certificate since all traffic to this api will be headless?
In my understanding, SSL provides the encryption for a request, and a certificate establishes trust for the end user. Because these calls to my webserver will essentially be headless, I'm thinking I don't need to worry about the trust establishment.
Am I correct in this thinking?
You will either need a self-signed certificate or a CA-signed certificate in order to use HTTPS on your server.
If your certificate is not assigned to you by a certificate authority, then any connection you make will trigger an error in your URLRequest that you will have to handle. The problem with an untrusted certificate is that a malicious man-in-the-middle could fake data to and from your server with his own self-signed certificate, and possibly pick up authentication credentials or data that he should not have access to.
If you are dealing with any authentication credentials or other private data, I'd recommend just requesting a signed certificate. If you shop around, you can find cheap signed certificates for $10-20 a year, which is a trivial cost to protect your users.
However, if this is just a personal project (the only data you have to worry about is yours), or any data that you will be sending is freely available, a self-signed certificate may be enough.
Good day!
In my asp.net web application I need to check incoming digital signatures of files. I do it by calling:
SignedCms.CheckSignature(false) or SignerInfo.CheckSignature(false) (C#).
And I want to ensure, that signers’ certificates during such calls are checked for revocation correctly, ensure that system settings are correct and to clear this process for myself.
Incoming signers’ certificates maybe of large amount of CA’s. So, the signer’s certificate may or may not include references to CA’s OCSP service or CA’s CRL service.
I want the system to check revocation in such way:
IF certificate has reference to CA’s OCSP web service then the system makes the request to CA,
ELSE
IF certificate has a reference to CA’s online CRL service the system downloads CRL and uses it
ELSE
System uses the local CRL.
Could you, please, answer my questions:
how (where) can I find the system settings which describe needed behavior? (Is this behavior changable or fixed?)
If the certificate has reference to CRL web service of CA, must I download and install the CA’s CRL by script periodically, or I can rely on the system downloads and uses them automatically when it needs CRL for checking?
Thank you.
The procedure is described in RFC 5280 and is very complicated. In brief, you do the following:
For certificate in question, check it's signature, validity period and key usage
Check the certificate against CRL.
Check the certificate against OCSP
For each certificate encountered during CRL and/or OCSP checking, perform steps 1-3 (this in turn can involve multiple CRL and OCSP checks).
I am not mentioning policy checks, which are very complicated, here.
It took me about a month to implement certificate validator for our SecureBlackbox library (but we have everything on our own, from CRL and OCSP clients to management of those CRLs). If you want to perform certificate checking using OS means, you should be looking for existing function that does the job for you.
You can find some useful information on getting internals of the CRL, more specifically on the CRL caching crl-caching-in-windows-and-little-bit
There are two approaches which i am thinking here, where, windows cryptoAPI will take care of handling the revocation by itself automatically including caching. But the issue here is that cryptoAPI will look for the CA server only when the current CRL in the cache expires. So there is the difficulty of maintaining the freshness of the CRL. But if your CA's CRL publishing frequency is on a daily basis, you may get away with this approach of using CertVerifyRevocation, function call from windows with appropriate configuration for some applications.
The second approach is to download and install the CRL from the CA server and use CertFindCertificateInCRL for validation. Your CRL down-loader application can be configured to update the CRL at a predefined time interval. This will work, if the CA publishes only Base CRL, as you get the entire revoked certificate list when you download your CRL every time. I donot know the answer, to what happens if the CA publishes the Delta CRL and the Base CRL at less frequent intervals.