Hot answers tagged

76

How does that work? They seem use an In-the-middle SSL Bump proxy. First, it works as a transparent proxy, meaning it will silently redirect all HTTPS traffic to SSL Bump proxy servers. You have to install and accept the proxy's Certificate Authority cert to make this work. Once done, each SSL connection is made from your host to the SSL Bump Proxy with ...


47

However, in this scheme, couldn't an impostor just present the certificate after getting it from the real server? An impostor cannot present, and take advantage of, the real server's certificate unless it also has the matching private key. This is true whether the SAN DNS entry or IP entry are used to identify the certificate being presented.


41

... change the public key in the certificate and send it to client. Digital signature is same, all the properties except public key are same. So how can browser understand the difference? The browser checks that the signature of the certificates fits the certificate. Since the public key is included in the signature and the public key is changed, the ...


25

At the end of the TLS negotiation (the "Finished" message), the client and the server take a hash of the entire conversation they've had so far, and they compare it. If it differs - as it would if someone performed a MitM attack on the certificate - then the connection is dropped. To quote RFC 5246: The Finished message is the first one protected with ...


24

Certificates don’t exist in isolation. To be trustworthy, a certificate must be signed by an issuer; these issuers are called Certificate Authorities. Each browser (or operating system) maintains their own list of a few hundred trusted CAs (called Root CAs) that it already knows and trusts; and your employer or school may have their own private issuing root ...


17

Is the only protection here that Bob actually checks that the public key on the returned certificate matches what he originally sent in his request to the CA? If the public key was switched before the CA used it to create the certificate, then Bob's web site won't work at all. The private key, which he has kept safe, will only work with his original ...


12

On eu-store.wacom.com, some images from their Amazon CDN are requested over http instead of https. This can be solved by installing HTTPS Everywhere and turning on "Encrypt All Sites Eligible": The gray padlock means all resources are served securely. So the webstore is most likely not compromised. They are still using an outdated cipher based on CBC and ...


7

Here are a few details that might help clarify the situation: Ports less than 1024 are (in most OSes) privileged ports that require root to run anything on them. This is intended as a security feature to make it more difficult for an attacker to host services on important ports on a compromised server. As a result, root is required to run anything on port ...


7

My questions are, why is this inconsistency happening This is known as mixed-content,where the page is loaded with HTTPS,while some parts(images) are loaded via Insecure HTTP. how can I verify that the store page is indeed wacom's As long as your system has not been compromised then the only way is to use HTTPS everywhere and visit the correct URL or ...


5

It is possible to do limited traffic analysis without doing decryption based on timing, size and direction of transferred data. For example HTTP/1 has a request-response pattern where the requests from the client are usually small while the responses from the server are much larger. Additionally the information in the TLS handshake often allow to distinguish ...


5

When the attacker sends the server's certificate, the client will encrypt a shared secret (used to generate the symmetric encryption key for the session) with the public key of that certificate. The attacker will then be unable to recover the secret since they don't have the certificate's private key, so they won't be able to complete the TLS handshake.


5

Is it dangerous to add a custom cert authority to a browser? It is pretty dangerous. The owner of this CA can use it for man in the middle attacks or to impersonate arbitrary web sites since your browser will trust the CA to create certificates for arbitrary sites. Using such attacks he can then intercept your passwords and other sensitive data. For ...


4

It's two separate things. LetsEncrypt set their certificates to be short-lived because they expect their users to constantly renew them, short-lived certificates limit the exposure time of a lost private key. Paid certificates are usually issued manually, and hence live a bit longer, for practical reasons (much harder to issue certs every 90 days when ...


4

This will help to protect against BGP Hijacking attacks. During a BGP hijacking attack, the attacker can re-route the traffic though its own servers, allowing him to perform a MITM attack. This allows him to create malicious responses to the challenges, which will be accepted by Let's Encrypt, and a certificate will be issued to the wrong person because of ...


3

Good question. The certificates of the most trusted CAs are normally included into software install package, e.g. into browser installer, into OS installer, or are preinstalled on device like smartphone. That's why the browser (or some other application) will notice if certificate is really from the specified CA.


3

On eu-store.wacom.com, some images from their Amazon CDN are requested over http instead of https Let me continue from that. Firefox says it's not 100% secure because it's loading unprotected content. I would say, naively... it's 95% secure Now, it doesn't mean the site wacom.com is not legitimate, but perhaps misconfigured. If you buy today from that site,...


3

I've seen many places refer to "256 bits certificates" in SSL encryption. You are most likely thinking about 256-bit symmetric cipher key sizes. There are no 256-bit certificates, but there are plenty of 256-bit symmetric keys (e.g. keys for AES, a common cipher in TLS). when I look at these certificates in browser I see 256 bytes instead. With the ...


3

The certificate and DNS record for IP public are irrelevant, you can buy any certificates without publish your sites. All you have to do is to prove you are the owner of that domain by clicking the approval link which send to your domain registration email or a DNS TXT record only.


3

HTTPS encrypts the content but: Anyone watching the stream, including your ISP, can easily see that you are going to www.bluebuggybumpers.com, or my.aids.results.com, or what have you. A VPN blinds your local ISP to where you go, although the VPN is capable of the same monitoring. The site you visit directly see's your IP address and can generally ...


2

The Tor Project hosts some bootstrapping servers called directory servers. They contain a list (a directory) with information about all Tor relays currently online. This info about each relay includes the public key. The directory is signed with one of the directory keys[1]. Those keys are distributed along with your copy of the Tor client[2]. Therefore, ...


2

In general, SSL/TLS does offer MITM protection. It encrypts data before it leaves your computer that only the endpoint can decrypt and vice versa. A MITM attack is ineffective against encrypted TLS connections because even if you intercept the public keys that the endpoints exchange, it still does not know their private keys. As for a Tor, it is not ...


2

For inspiration, look at how SSH key exchange works: The client maintains a table of "known servers" that matches an IP address to a hash. When connecting to a server, the client receives the server certificate (public key) and computes the hash of it, and looks up the server's IP address in the "known servers" table. If the client has seen this server ...


2

Would this be sufficent in terms of being able to securly access PHPMYAdmin and upload files or should I be using SSL aswell? I am guessing you are talking about Secure socket tunneling to run the localhost on the remote server as given here. The secure socket tunneling protocol already does SSL/TLS provides transport-level security with key negotiation, ...


2

If you are asking whether or not an HTTPS connection will show the unencrypted URL in the network data, then the answer is partially YES. Contrary to the previously accepted answer, the URL does not get encrypted like the rest of the data. The base URL (ex. amazon.com) will appear as Server Name Indication extension (SNI) unencrypted data. Only the base ...


2

The same as using plaintext (unencrypted and unauthenticated) communication elsewhere. What exactly that means, depends on your threat model. Smart Bulb, Dumb Protocol Imagine you had a smart lightbulb in your home. You could use an app to control the brightness and the warmth of the bulb. It even offers an API, so you can control it via a Raspberry Pi ...


1

Their server connects to your HTTP server and/or to your authoritative DNS server (depending what kind of validation you choose to use) from multiple different data centers connected to the internet backbone through different Tier-1 ISPs. Imagine they host their own servers in multiple cloud regions and require 9 confirmations from (AWS, GCP and Azure) by (...


1

No, such a thing does not exist in any TLS standard. As per the name, TLS works on the transport layer and has no knowledge of the inner protocols. The URL gets encrypted just like the rest of the data. Keep in mind that in HTTP, data can be part of the URL. This is known as 'URL parameters' or 'GET parameters'. You might still want to consider an MITM ...


1

Apache om Debian 9 (Stretch) uses OpenSSL 1.0.2 (see apache2-bin dependency on libssl1.0), so you can use the approaches documented in that linked post. You can modify the startup script to export LD_PRELOAD=/path/to/libsslkeylog.so and SSLKEYLOGFILE=/tmp/your.keys. How to do so is dependent on the application. For systemd you could try systemctl edit ...


1

The private key is linked to the certificate, so if you use the same certificate at different places, you also need to use the same private key. If you want each server to have a different key, you need to generate different certificates.


1

Asymmetric private keys have two basic operations: they can Sign a message such that anybody with the corresponding public key can verify that the private-key-holder signed it and it hasn't been tampered with, and they can Decrypt a message that was encrypted using the public key. In addition to the direct usefulness of these operations, the private key can ...


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