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13

My understanding is that Superfish installs the exact same certificate and private key into every computer, so once you obtain the hard-coded private key you can use it to man-in-the-middle anyone who has superfish installed. Avast does not do this; it dynamically generates a unique certificate and private key for every install. This is what the Avast ...


7

First, a couple of points. In any cryptographic system that does not provide information-theoretic perfect secrecy, the key can always be brute-forced. One of the key components of determining whether a cipher is secure is whether or not it is feasible to brute-force keys, and if it is, the cipher is not secure. So, brute-forcing the key isn't an ...


6

Hopefully, someone will do the testing and give a definitive answer for Kaspersky for you. Meanwhile, here's an answer for the general case: It depends. Does running an SSL proxy against yourself weaken your security posture? Certainly. Will any given product weaken your security posture as bad as Superfish? That's very implementation-dependent, and also ...


4

The asymmetric cryptography establishes a shared secret, which is called, in TLS terminology, the master secret. The master secret is fixed throughout the session; a TLS session consists in one or several connections (opening a new connection while reusing the master secret is called session resumption and uses the "abbreviated handshake"). For each ...


3

In CBC mode the IV is applied after the decryption algorithm with the key is applied to the ciphertext. Which means that if your key is correct, but your IV is wrong then the first block will come out garbled. The rest of the decryption will happen correctly since the each IV afterwards is the previous ciphertext (hence the name Cipher Block Chaining). ...


3

As long as the machine in question has enough entropy to generate strongly random keys and nonces, that's totally correct. The key must never leave that server. Even more, if I were working on a critical application, I wouldn't even trust that machine and keep the key in a HSM. It might cost a lost, but it significantly enhances the security. There is a ...


2

Superfish acts as a Man In The Middle. It dynamically generates keys which your browser trusts for domains you visit. To generate those keys it needs the private certificate, and while more obfuscation is possible, in the end it can't conceal that key. What could be done though is to generate a unique key pair for the Certificate pair on each computer ...


2

Based on another major Superfish update: Komodia client side SSL verification is broken! The major problem with SSL Intercepting proxies (or any in-house crypto software) developed by OEMs or a third party like Komodia is that you can't really trust them (especially after the Superfish buzz)! TLDR of this new update: An attacker does not even need to ...


2

TLS can protect against an eavesdropper which has only access to the communication channel between both parties. But it needs to be properly implemented, that is strong ciphers, proper validation of the peer etc. It will not protect against attacks against the endpoints itself. That is it will not help you if there are bugs in the used TLS stacks (like were ...


2

The page on GRC actually explains why this occurs. Google has a massive infrastructure, and uses many certificates to protect HTTPS traffic, not just one. Each of these certificate has a different fingerprint, of course. So, even though you see two fingerprints above (because there are two different certificates here, one was used when you access the ...


2

By trusting the Root CA you're trusting their judgement in who they sign. As long as the intermediate CA is valid, not revoked, and you're trusting the Root CA... the chain will always be verified. Other applications (such as NSS) can add additional checks and functionality to provide this, but unless the application provides it it's not really part of the ...


2

From wiki: The HSTS Policy[2] is communicated by the server to the user agent via a HTTP response header field named "Strict-Transport-Security". HSTS Policy specifies a period of time during which the user agent shall access the server in a secure-only fashion. In short, just trim out this response header field to the browser and it will never know that ...


1

So BREACH is an attack specifically against response bodies, not headers. Since cookies are sent as headers, they aren't susceptible to the technique described by BREACH, but have been vulnerable to other compression side-channel attacks such as CRIME. What they mean by: (2) Reflect user-input in HTTP response bodies, AND (3) Reflect a secret (such ...


1

These are the golden rule of computer security: "It is impossible to hide anything from a competent user with system administrator privilege" and "any competent user with physical access to the device can always elevate himself to system administrator". You cannot hide any information from someone with physical control of the machine. If the secret you are ...


1

you can run following command in a command prompt (with administrative rights): certutil -setreg chain\minRSAPubKeyBitLength 512 this will set back the required key length (less secure!) see https://morgansimonsen.wordpress.com/2013/05/30/what-does-the-this-certificate-has-an-invalid-digital-signature-message-actually-mean/ for more information. quote ...


1

I don't think you could do this with the usual applications.. If you have your own application using the OpenSSL library you could handle this condition inside the certificate verify_callback. This callback is called on verification for each certificate in the trust chain and you can distrust the certificate by just returning 0. Note that this will cause ...


1

If you don't intend to perform client authentication via SASL or the like, a certificate is needed only for the server. Just embed the public key you generated in the app and use it for certificate pinning. If get your certificate signed by a CA in Android trust store, you can use Android TLS utilities without any extra step, since the verification will be ...


1

The answer as to why you cant simply take the signed public key and use it to intercept traffic in a man-in-the-middle style attack is that you (or the attacker) wont have the corresponding private key that goes with the public key. So the browser will receive the web servers or the CAs signed public key, and will use that to encrypt its own secret to send ...


1

I did everything that raz mentioned in his answer - the https://filippo.io/Badfish site checked out OK, I had nothing named "Visual Discovery" in my Add/Remove Programs, and I found no Superfish certificates in mmc or Firefox. But I still found a variant of Superfish on my machine, and I don't even have a Lenovo computer. I searched for filenames ...


1

Weak ciphers are potentially susceptible to man-in-the-middle (MITM) attacks. On certain networks such as open Wifis in a coffee shop, a malicious attacker may break the encryption and decrypt the HTTPS traffic. However attacks against RC4 are impractical according to this article from Qualys



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