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1069

General SSL (and its successor, TLS) is a protocol that operates directly on top of TCP (although there are also implementations for datagram based protocols such as UDP). This way, protocols on higher layers (such as HTTP) can be left unchanged while still providing a secure connection. Underneath the SSL layer, HTTP is identical to HTTPS. When using SSL/...


641

Since the general concept of SSL has already been covered into some other questions (e.g. this one and that one), this time I will go for details. Details are important. This answer is going to be somewhat verbose. History SSL is a protocol with a long history and several versions. First prototypes came from Netscape when they were developing the first ...


565

This attack is supposed to be presented 10 days from now, but my guess is that they use compression. SSL/TLS optionally supports data compression. In the ClientHello message, the client states the list of compression algorithms that it knows of, and the server responds, in the ServerHello, with the compression algorithm that will be used. Compression ...


387

It is the magic of public-key cryptography. Mathematics are involved. The asymmetric key exchange scheme which is easiest to understand is asymmetric encryption with RSA. Here is an oversimplified description: Let n be a big integer (say 300 digits); n is chosen such that it is a product of two prime numbers of similar sizes (let's call them p and q). We ...


337

After the lengthy presentation of SSL in the previous answer, let's go with the fun stuff, namely: Attacks on SSL There have been many attacks on SSL, some building on implementation errors, others on true protocol weaknesses. One must remember that while SSL is one of the most attacked protocols (since it is very high profile: a successful application to ...


271

This is an active area of research. I happen to have done some work in this area, so I'll share what I can about the basic idea (this work was with industry partners and I can't share the secret details :) ). The tl;dr is that it's often possible to identify an encrypted traffic stream as carrying video, and it's often possible to estimate its resolution - ...


266

What is the Poodle vulnerability ? The "Poodle" vulnerability, released on October 14th, 2014, is an attack on the SSL 3.0 protocol. It is a protocol flaw, not an implementation issue; every implementation of SSL 3.0 suffers from it. Please note that we are talking about the old SSL 3.0, not TLS 1.0 or later. The TLS versions are not affected (neither is ...


239

To understand the attack, one must recall Bleichenbacher's attack from the late 20th century. In that attack, the attacker uses the target server as an oracle. When using RSA-based key exchange, the client is supposed to send a secret value (the "pre-master secret") encrypted with the server's public key, using PKCS#1 v1.5 padding (called "type 2"). ...


225

Don't install their certificate on any device/OS installation which you ever want to use for private activity. Once you do, your traffic is subject to MITM attacks even if you are not using your college's network. Such an attack requires having the private key for the certificate you installed, but in practice this is quite easy because these "security ...


207

How does HTTPS work? HTTPS is based on public/private-key cryptography. This basically means that there is a key pair: The public key is used for encryption and the secret private key is required for decryption. A certificate is basically a public key with a label identifying the owner. So when your browser connects to an HTTPS server, the server will ...


207

@paj28's comment covers the main point. OpenSSL is a shared library, so it executes in the same user-mode address space as the process using it. It can't see other process' memory at all; anything that suggested otherwise was wrong. However, the memory being used by OpenSSL - the stuff probably near the buffer that Heartbleed over-reads from - is full of ...


202

According to Google, the difference is with handling referrer information when clicking on an ad. After a note from AviD and with the help of Xander we conducted some tests and here are the results 1. Clicking on an ad: https://google.com : Google will take you to an HTTP redirection page where they'd append your search query to the referrer information. ...


201

Typically certificates are validated by checking the signature hierarchy; MyCert is signed by IntermediateCert which is signed by RootCert, and RootCert is listed in my computer's "certificates to trust" store. Certificate Pinning is where you ignore that whole thing, and say trust this certificate only or perhaps trust only certificates signed by this ...


172

It's not just about you. By forcing users to use TLS, they're creating a more secure environment for everyone. Without TLS being strictly enforced, users are susceptible to attacks such as sslstrip. Essentially, making unencrypted connections an option leads to the possibility of attackers forcing users into unencrypted connections. But that's not all. ...


163

There are two objects: the private key, which is what the server owns, keeps secret, and uses to receive new SSL connections; and the public key which is mathematically linked to the private key, and made "public": it is sent to every client as part of the initial steps of the connection. The certificate is, nominally, a container for the public key. It ...


162

For usability reasons you need to offer a redirect to HTTPS from all HTTP URL:s. Otherwise first time visitors who simply enter example.com/some/page into the URL bar of the browser will be greeted by a connection error. Serving the redirect does not make you more vulnerable. Users who don't have your HSTS entry in their browsers will make a HTTP request ...


158

I mean, my WiFi is protected, so all the communication should be encrypted, right? It is, but not at the place you're reading it. Encryption happens at a certain point in the "pipeline", and decryption then must also happen at a certain point in the "pipeline" (otherwise the data are useless). You are observing the data after they have been decrypted, which ...


155

OpenSSL s_client To check if you have disabled the SSLv3 support, then run the following openssl s_client -connect example.com:443 -ssl3 which should produce something like 3073927320:error:14094410:SSL routines:SSL3_READ_BYTES:sslv3 alert handshake failure:s3_pkt.c:1258:SSL alert number 40 3073927320:error:1409E0E5:SSL routines:SSL3_WRITE_BYTES:ssl ...


154

What is there to secure it from? It's loaded directly within the browser. There is no connection outside of the local user context of the machine meaning there is nothing to intercept / tamper with. To modify what you see you'd have to either modify the browser executable, memory space or modify the underlying data used to store the settings. To read the ...


151

Summary: capability URLs are more secure than many people give them credit for, but not suitable for all applications, and require extra care to use. These type of URLs are commonly known as capability / secret URLs. It's meaningless to talk about security without specifying a threat model. Here are a couple that come to mind: 1: A passive attacker on the ...


146

You can have some serious fun playing with printers, photocopiers and other such devices - even UPSes. Security is usually an afterthought at best, if not totally absent. Stuff I've seen: Default credentials used everywhere, and web-based config panels storing passwords in plain-text, often within a generated config file. I've never seen anything better ...


139

A VPN is certainly a good solution, provided they don't block that, too. The best solution for protecting your privacy, though, is probably to try your hardest to get this policy overturned. This is an absolutely abhorrent 'security' policy. It's literally a built-in man-in-the-middle attack against everyone on campus. If their firewall becomes compromised, ...


138

This is more of a problem than you think, particularly for a company like Google, because they're a frequent target for this type of shenanigans. But there are several layers of safeguards, and our protection is getting better over time. Your first line of defense is the Certificate Authority. They shouldn't let certificates be signed inappropriately. Each ...


137

Can you explain why browser security should be placed on the top priority ... Because the browser is processing lots of untrusted content from the internet. Of course, if you use any other programs which does this (like Mail client, maybe Office program, PDF reader) you should keep these updated too since vulnerabilities in these programs are a regular ...


131

Here's a really simplified version: When a client and a server negotiate HTTPS, the server sends its public key to the client. The client encrypts the session encryption key that it wants to use using the server's public key, and sends that encrypted data to the server. The server decrypts that session encryption key using its private key, and starts using ...


130

The common web application attack vectors don't apply to a strictly static website. Without interactive elements there are no accounts to hijack or cookies to steal. Nonetheless, you should provide your visitors with encrypted access - even if you're not hosting delicate content. TL;DR Use HTTPS with HSTS to ensure some degree privacy and the integrity of ...


129

I think you are misunderstanding what a SSL certificate actually certifies, and what it is designed to protect against. A standard certificate only certify that the owner of the certificate actually controls the domain in question. So a certificate for g00dbank.com only certifies that the owner controls the g00dbank.com domain. It does not certify that the ...


127

Whilst I don't know the specifics of your ISP, I would say that it's likely that what they're doing here is intercepting all traffic you send over the Internet. In order to do that (without you getting error messages whenever you visit an HTTPS encrypted site), they would need to install a root certificate, which is what you mention in your post. They need ...


119

Yes, you should absolutely reject the CSR. Additionally, you should change your hosting provider as it looks like they don't know what they are doing. It is already bad enough that they sent you the private key via e-mail i.e. via an insecure medium. However, they also Cc'ed it to someone else, which is a complete breach of confidentiality. Furthermore, I ...


118

It's not uncommon, but it may not be required. A lot of developers seem to forget that HTTPS traffic is already encrypted - just look at the number of questions about implementing client side encryption on this website - or feel that it can't be trusted due to well-publicised issues such as the Lenovo SSL MitM mess. However, most people weren't affected by ...


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