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3

First off, an important notice: DO NOT ATTEMPT TO WRITE YOUR OWN CRYPTO! This includes using known cryptographic routines in a way that isn't standard. if you intend to follow the standards, then you should use a library designed 8and maintained) for that specific standard. That being said, every time you encrypt a file using a public certificate (using, ...


2

Actually, there is an often unused (at least on the web) optional part of SSL/TLS that allows for client authentication. It is generally not used on the web because the server doesn't really care if the client is who they say they are - they just need to have the proper credentials. Additionally, imagine the nightmare of having to verify every client in the ...


9

No. There's no such thing as a message sent from https://example.com to anywhere; a message is sent from a device, not a URL. A user visiting your site sends messages from their computer to your server, and your server sends messages to their computer; the https in the URL means that they initiated that connection with the HTTPS protocol, and your server ...


0

User's Security You are missing one extremely important thing: CSRF mitigation. Be sure to fully understand the related problems. Tldr: in addition to the authorization token (e.g. session cookie), you need a challenge per action to identify if the action is intended by the user or unintended. Fix JSONP leaks. X-Content-Type-Options: nosniff, on all ...


2

You can not generate your own EV certificates and especially you can not generate self-signed EV certificates. Only some CA's are able to generate these and these CA's are specifically marked in the SSL stacks of the browser or operating systems. If you want to create EV by yourself you would have to change the SSL stack used by the browser to accept the ...


1

HPKP does not address this need. HPKP is an extension to the HTTP protocol allowing website administrators to provide specific pining information to the browser, allowing: To check that at least one of the certificate composing the authentication chain of the current HTTPS connection (depending on the platform architecture architecture, the server ...


18

This client behavior is prohibited by section 8.1 of the RFC: If an HTTP response is received over insecure transport, the UA MUST ignore any present STS header field(s). The spec prohibits severs from sending insecure HSTS directives and clients from processing insecure HSTS directives. This ensures that a faulty implementation in either a server or ...


3

This may be to avoid the use of this header to cause a denial of service attack. Imagine an insecure HTTP-only website. Now imagine someone able to tamper with the HTTP headers sent by this site to add an HSTS header. According to the RFC: The UA should stop trying to access the site through HTTP, and try to use HTTPS only instead. If the UA is unable to ...


0

The abbreviated handshake is used in re-establishing a previously agreed secure connection, which means it will use the same keys as it used for the previous session where a full handshake was used to initiate the connection and agree on the keys and ciphers etc. See Speeding up SSL: Enabling session reuse


1

If an OAuth 2.0 token is compromised, you only need to concern yourself for the TTL of the token. If an HTTP Basic Auth header is compromised, the credentials do not expire. You would manually need to change your client_id and secret, and that's if you even knew or thought they were compromised. And it's likely you would need to change your client code ...


2

What I would say about the options that you outline is that HTTP Auth with SSL is a simpler but less flexible option and Oauth2 is more complex but has more flexibility in what you can achieve with it. One example, as you've noted in your ASCII art diagram, with OAuth2 it is possible to create a token which can be used in place of the password to ...


2

Your organization is most likely using a man-in-the-middle ssl cert. They have a program or proxy setup to authenticate your certificate as valid then submit another certificate to the website on your behalf. This is common for companies that must rely on pci or hipaa compliance. Unfortunately, when this is done then your passwords are exposed by this ...


5

There are lots of information about this topic on the internet and on this site, so it does not make sense to repeat everything: a short introduction on how this works you'll find at http://www.zdnet.com/article/how-the-nsa-and-your-boss-can-intercept-and-break-ssl/ and a discussion of the associated problems at What security risks are posed by software ...


0

I don't know how the audio playing is done on the device, but if an external application outside chrome is used for download the content, then the problem might be the use of SNI (Server Name Indication). Some Android applications still have problems with SNI, especially if they where built with Apaches HTTP client library. But, your site requires SNI. That ...


0

The data in the cert is hashed and the hash is sighed with C's private key. C's public key is in the cert. All of this is hashed and signed by a CA's key. Changing the subject changes the hash, the new cert is bad without even verifying the first signature.


3

Edit: I realise that this may not be clear from the answer below... but from the point of view of your application, it doesn't really make any difference whether you run the PKI/CA yourself or whether you use one or more third-party CAs. Even if you choose to run your own PKI, you really don't want to code it yourself - so you'd use one of the existing ones, ...


1

I think this extension is quite simple and generally safe to use for two reasons: Firstly, on Q. When does HTTPS Everywhere protect me? When does it not protect me? section on HTTPS Everywhere website FAQ page HTTPS Everywhere depends entirely on the security features of the individual web sites that you use; it activates those security features, ...


0

Generally what happens in a https connections is that client asks for SSL certificate from the SSL compliant server it is communicating with over https. Server will provide a certificate from it's key store. After client receives this certificate it validates it's credentials depending on whether hostname is same as requested has a verifiable chain of ...


1

Are you using Firefox? If so go into Tools->Options->Advanced-> and choose view Certificates. Delete or distrust it. I believe if you want to be "safe" you should make the certificate chain the same path when viewing from the the same computer. When I did this from Firefox the certificate chain was then the same as presented from Chrome.


1

Wildcarding your certs as a countermeasure would be considered security by obscurity and as such is not really helpful. Your sites can be listed in other databases and there is only finite number of IP addresses out there anyway so it doesn't really matter how hard you try to hide. Eventually they'll find you and you have to be prepared for them. It can ...


1

Both the goal and the approach are rather questionable. Users don't have HSMs in their PC (unless you're all working at a very special company which somehow provides its employees with crypto hardware). At best, you'll encounter a user with a smartcard, but even then they probably won't use the card for your site, because it's just too cumbersome. A more ...


0

StartSSL provides free Class 1 Web server certificates (SSL/TLS) & Client and mail certificates (S/MIME). I use them for both my website and email. Verification is done automatically and your clients would often get the certificates almost instantly. This is better than you operating a PKI and issuing the certificates yourself. You can check the client ...


0

I would suggest that as Windows XP is now out of support (apart from organisations that have purchased extended support from Microsoft) that for most sites it would be reasonable to cease supporting it. However to weigh this up, it's really a site-by-site consideration. Key factors could include What percentage of users of the site currently use Windows ...


0

Is this really a good idea? Yes, it could work, but... In case of a simple MITM attack, what will happen? Your server won't recognize hacker's client cert and will return to login page. The user will naturally re-enter his credential and so could work normally again. But from there, your server will accept hacker's cert, as long client don't try to ...


3

The risk/issue is exactly the same and the mitigation as well. Regardless if it loads the database partially or completely into memory. There will be no way for you to tell which keys have been compromised and which haven't. So the only option would be to revoke them all, regardless if it's a Redis or SQL database. Most of the time the reason why people are ...


1

DSS is a digital signature scheme published (but not invented) by the NSA. In TLS (TLS1.0, PKIX) it serves the same function as RSA and ECDSA: digital signatures prove that the server you're talking to has the private key corresponding to the public key in the certificate and that the information in the certificate (including the server's public key) is ...


1

What can I do to prevent described attack? WinSCP installer binaries are signed with Authenticode, so you should be able to right-click-properties the .exe and check the signer. Of course you would have to know that Martin Prikryl is the legitimate author, and you would have to trust Verisign to have made sure that's who it really is, and you'd have to ...


2

I agree that it would be nice to have this site available by https so that the transport from the site to the user is protected. But I think one should put this risk into relation to the risk which remain even if the site has https: How did you know that you must visit winscp.net and not another site like winscp.org (ads), winscp.com, download-winscp.net ...


1

Access can be controlled for local processes accessing local network assets like for example network ports. By associating labels with port objects and userids, groupids associated with processes (even individual processes, allowing you to specify whether and how an entities associated with particular labels can operate on or interact with entities ...


0

Typically you verify a vulnerability in three ways: Run exploit code. Did it blow up? Check your package manager's documentation. Do you have their version? Check the code. Do you have the affected lines? Since #3 is not effective for binaries, and you do not want to run exploit code, your other option is updating. I'd imagine by now that every distro ...


1

Generally, the very nature of PKI (and some good system maintenance) should prevent this from being a security risk. But personally, I'm not sure I'd really want just any website to be able to enumerate my Trusted Root CA list. This sounds like a good way to phish out systems vulnerable to attacks using stuff like DigiNotar certs or certificates from other ...


2

I work for a penetration testing company that requires a client certificate to log into any of our testing hosts. The certificates do require you enter a pass phrase when authenticating. This is done as an added layer of security, not to replace the need for passwords. If the certificate does not require a pass phrase, then yes - letting someone get a ...


0

Edit: Could I use JavaScript to send a GET or POST request to the server, providing a certificate that the CA I'm checking for has to sign? If the connection fails I'll know that the root CA isn't installed on the client. That's probably the best thing you could do. You still can get false negatives if the TLS handshake fails for some other reason ...


1

No, the web server cannot check to see all the CA's the client has installed. If you have access to the client machine, you can check by viewing the Trusted Root Certification Authorities store.


1

I doubt that it is possible to add custom cipher suites to Chrome or Firefox and to keep these maintained with all the rapid updates. I don't know about adding ciphers to the Windows system so that they can be used by IE, but given that even Microsoft itself has serious problems in this area I doubt that you can easily add ciphers there and keep them cheaply ...


2

(I can't find any documentation that goes into which order I specifically need it in, and which certificates I actually need to include). RFC5246 is pretty clear on this: certificate_list This is a sequence (chain) of certificates. The sender's certificate MUST come first in the list. Each following certificate MUST directly certify the one ...


2

Some companies have proxy servers that perform a MITM attack on all https traffic going through a company. So while SSL3 may be disabled on your browser, it might not be disabled on the proxy server, and the proxy server is what establishes the SSL connection to the test servers you're accessing. If that's the case, you need to update your proxy server to ...


0

Using the updated browsers isn't the mitigation for POODLE attack. The protocol SSLv3 should be disabled from the browser so that it starts a session only with TLS v1.0 . The mitigation for POODLE attack includes: 1.Disabling the support for SSLv3.0 from the server. 2.Disabling the support for SSLv3.0 from the browser. 3.Prevent TLS downgrade attacks by ...


2

the first security hole is your shared "el-cheapo" server. if you can not trust your machine, you can not trust your applications. what this means is that if you have no controle over the machine itself, adding security to it is pointless, an attacker will just attack your webserver instead of your connection and makes sure he can do anything he/she wants ...


0

No, and it doesn't seem likely to be added as a feature. See https://code.google.com/p/chromium/issues/detail?id=107793#c20 I'm just deeply concerned about the code complexity cost here, which increases the opportunity for both performance and security bugs. - rsleevi@chromium.org


0

Yes definitely you can use two different SSL certificates for single domain. You have to use wildcard SSL certificate for the rest of sub domains and then configure multi domain UCC certificate for the particular domain for which you don't want wildcard Certificate. You must understand how wildcard SSL Certificate works.. Once you install wildcard SSL on ...


0

On both the server and client side there must be support for SNI (Server Name Indication) in order to serve two different certificates for one domain/IP. SNI allows the client to specify the hostname when making a request, and thus have the server provided the correct certificate. Notably, on the client side, no versions of IE on XP support SNI. On the ...


1

Can two of these certs co-exist for a single domain and not cause clash? As long as both certificates are valid and match the hostname it should be no problem from the client side.


3

Judging from the IETF mailing list it was forgotten inside the RFC document. Relevant mail is the second in the thread: Good point. DTLS is intended to support extensions--and OpenSSL, at least, supports them in the same way as it does for TLS. There probably should be a definition of ExtendedClientHello in 4346 and 6347, but it's exactly ...


0

The server will indeed have and announce to the client (during SSL handshake) a list of trusted client CA, and the client will have to provide a client certificate signed by a CA on that list. you said: In this way Server may be loaded with various Client Certificates? I guess you meant "Client CA". The server wouldn't be pre-loaded with the actual client ...


0

Comment to @user54791 and @iszi's comment: Avast shields untrusted certificates with a certificate issued by a different issuer, called "avast! Web/Mail Shield Untrusted Root". As long as this issuer stays untrusted, there is still a security warning when a HTTPS connection with an untrusted certificate is accessed. So there is no need to disable HTTPS ...


1

If the thieves man-in-the-middle connections to saas.example.com and present the wildcard cert, would the customer getting man-in-the-middled get any sort of SSL-related warning from their browser? Usually not because the attacker presents a non-revoked certificate which is valid for the accessed host. The client would only reject the valid certificate ...


3

Use of SHA-1 is irrelevant here. The problem with a self-signed certificate is that there is no way for anybody to verify that the certificate is the correct one or not; this is exactly what the client warnings mean. When one of your staff sees the warning, and he clicks through to connect nonetheless, then that user could be connecting to a fake VPN ...


2

Basically, a man-in-the-middle attack could occur. If someone were to listen in on your users when they submit their username and password, that person would be able to retrieve their login credentials. Any decent network password sniffer could easily pull this off.


27

Your certificate only contains a sha1 signature, probably with a lifetime past 1 January 2017. These are deprecated, and Chrome therefore removes the appearance of security. See https://googleonlinesecurity.blogspot.com/2014/09/gradually-sunsetting-sha-1.html for more info.



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