New answers tagged

1

Client-side hashing can be combined with server-side hashing if you want, but server-side hashing (using a slow, salted hash, typically one of - in descending order of strength/modernity) argon2, scrypt, bcrypt, or PBKDF2 - is essential. You can re-hash something that was already hashed on the client. However, if you were to just take the hashed password ...


1

The sole purpose of a salt is to increase the difficulty of brute forcing multiple passwords by preventing someone who obtained a list of N hashes of attacking all N hashes in parallel (or combining work of prior attacks). If an attacker can inject javascript and change the salt used sent along with the password, they could also inject javascript to just ...


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No. The client connection to the webserver may be secured using TLS, commonly known as https. The connection from the web server hosting shell-in-a-box to the server you are controlling may be via ssh.


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Is PCI DSS standard requirements regarding TLS applicable only to customer facing webs or to whole even internal networks? "It depends" is going to be the answer. If you have administration channels for you're devices (RDP, HTTPS, etc) and they use TLS, then requirements 'Strong Cryptography' will apply for them as well. They aren't directly 'SSL/TLS' ...


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I have seen at least two commercial firewalls operating SSL TLS filtering based on server certificate (or client SNI request). My answer will be from the protocol point of view: no code supplied. Basically the proxy will not try to intercept the TLS conversation itself, but rather judge from the handshake conversation that mandatorily occurs in plaintext. ...


1

The exact verification done with client certificates depends on the use case. For example in SIP (voice over IP) it is common that the same same system can be both client (initiating a call) and server (accepting a call). In this cases it is common that the same certificate is used as client and server certificate and that it contains the hostname of the SIP ...


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You could force your browser to treat the site as though it has HTTP Strict Transport Security (HSTS) enabled. HSTS makes the browser re-write any HTTP navigation (within the specified domain) to HTTPS, before sending the request. As a general rule, this isn't something that is exposed to the user, but there are a few ways you could do it. For example, you ...


2

Theoretically speaking, the answer is, of course, "It depends." Practically speaking however, for the client side the answer is "probably not" and the answer for the server side is "yes, with caveats." Client-side: This is the situation you're describing. You visit a site with your browser, explicitly specifying the HTTPS protocol, and are immediately ...


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1) Is there any way that I as a client can establish if there is a MITM/attacker which is denying/redirecting HTTPS connection? (this cause is suggested by the "HTTPS Everywhere" plugin) Totally depend on site configuration: the redirect may be set only to frontpage or for all ressources. There's no generic answer to this question. Nevertheless, since HTTPS ...


1

From the report by SSLLabs: Chain issues Incomplete This is a misconfiguration of the server: it is not sending the full certificate chain up to (but not including) the root certificate but instead only sends the leaf certificate. Specifically it is missing the intermediate certificate for RapidSSL TLS RSA CA G1. Without knowledge of the intermediate ...


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As you ask in Steffen's answer about is it safe to use email while using VPN, if you don't trust on this VPN, you can set Google's DNS directly on your MAC and stop using this VPN. To do this, go to System Preferences and then Network Preferences. Go to DNS tab and put 8.8.8.8 on DNS #1 and 8.8.4.4 on DNS #2. Actually, your problem can be restrict to your ...


1

This looks like a man in the middle attack but not on your computer but instead on your network - otherwise the problem would likely not vanish if you use Tor or VPN. This might be because you are using an insecure network (like an open WiFi hotspot) where somebody is doing an attack or because your private network is compromised. The latter could be for ...


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There is no requirement in PCI DSS to encrypt cardholder data in transit over private (ie not the internet and not wifi) networks. Therefore if you are using early TLS or SSL on an internal wired network it is fine (according to the standard) to continue to use it. See requirements 4.1 Use strong cryptography and security protocols to safeguard sensitive ...


2

On a Skylake (i7-6700hq) laptop, on a single core: $ openssl version OpenSSL 1.1.1 11 Sep 2018 $ openssl speed -evp aes-128-gcm $ openssl speed -evp chacha20-poly1305 $ openssl speed -evp aes-128-ccm The 'numbers' are in 1000s of bytes per second processed. type 16 bytes 64 bytes 256 bytes 1024 bytes 8192 bytes 16384 bytes aes-...


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Payment data should be encrypted in transit and at rest for every step in the process. SSL and TLS 1.0 are now depreciated, e.g. disabled on payment gateways to force merchants to properly encrypt upsteam connections, but for internal processing you have more choices than what is supported by browsers but you will have to dig into technical docs to work out ...


3

They will be requested if the client supports them and if they are enabled. Like you mentioned, for example, OpenSSL does not enable them by default. They don't seem to provide any justificative other than it's "rarely used". But consider that most desktop CPUs support instructions for accelerating GCM, making it probably faster than CCM.


3

As far as I know internal SSL is also required. CC data needs to be encrypted in transit, and that includes both public and private networks. Depending what your apps connect to it it also means connections from applications to the DB/messaging systems/you name it... and also if you use an CDN/SSL accelerator like Akamai, the SSL accelerator shouldn't see ...


2

They are all sent together by the server All certificates, except for the root certificate, are sent together as one bundle. Technically, you may include the root certificate as well, but it will be ignored by the client. If the server only sends the "leaf" certificate, then it depends on the browser if they are able to somehow get the missing ...


0

Let me explain what all of these files are and what they mean. Then the solution will become more obvious: What is a public and private key? Public and private keys are two parts of a key, used for asymmetric encryption. They are mathematically related, and are generated together. The public key, as the name suggests, can be made public without any loss of ...


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SOCKS5 by itself just make sure that the necessary TCP connectivity to the target is created and that all data are forwarded between client and server. It also might do a DNS lookup to resolve the hostname. A plain SOCKS5 proxy does not change anything with the payloads or changes the requested target server which means that HSTS will continue to work the ...


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Domain names are a different addressing scheme than IP addresses: There might be multiple IP addresses for the same domain name and there can also be multiple domains on the same IP address. And these domains can serve different contents too, even if they have the same IP address (at least with HTTPS). Only if there is a 1:1 relation between IP and domain ...


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My confusion stems from reading that TLS handshake uses some kind of Diffie Hellmann, when I was certain that the symmetric key was generated by a digest of earlier packets encrypted with clients public key and safely decrypted with servers PK. The key exchange is used to generate the symmetric key (or at least the pre-master secret which the keys are ...


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Major browsers and operating systems don't support this. You could try using HPKP, however beware that HPKP is dangerous, especially for public websites. It can achieve what you desire, but it is tricky to achieve and failing can completely block the domain for years. It will also work for (or block) all visitors, not just one PC. EDIT: Support for HPKP ...


3

Yes, there is a difference. On Windows, Google Chrome uses a built-in Windows Certificate Store when identifying the trust. Mozilla uses its own trust certificate store. Apparently, your internal CA is installed on Windows, but not in Firefox browser. You have to install your private root CA certificate into Firefox browser.


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HTTPS not secure can be caused for multiple reasons but usually has to do with the certificate being used. In chrome you'll want to view the certificate details and see if anything is awry such as ... - untrusted issuer - name mismatch - date is expired - date is the future It could also be that your PCs systems clock is way behind or way ahead causing ...


3

I feel that a technical answer is not really possible here, or would really be accepted (as that is dealt with in the linked answer), but something more esoteric, if not the direct answer to your question, will at least provide interesting reading for some and food for thought for others. Moxie Marlinspike has long held the belief that the CA trust model is ...


5

So who decides what CAs are trusted? The browser and OS vendors do. Why cant a regular users CA become trusted? He can apply to be a public CA, but it is unlikely that the user is able to match all the security guarantees required by the browser/OS vendors for a publicly trusted CA. Even several commercial CA failed these requirements. But nothing ...


1

A possible scenario for Case 4 is one where a MITM replaces an image with one that exploits an RCE (remote code execution) vulnerability in the user's browser. Here's an example of such vulnerability: https://nvd.nist.gov/vuln/detail/CVE-2017-2416 --basically you can serve a crafted image containing executable code and have that code executed on older ...


1

Another reason why warning about mixed content is a good idea is that a MITM can replace an "insecure" image with one that exploits an RCE (remote code execution) vulnerability in the user's browser. Here's an example of such vulnerability: https://nvd.nist.gov/vuln/detail/CVE-2017-2416 --basically you can serve a crafted image containing executable ...


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IP and domain cannot be easily spoofed. Spoofing the source of a TCP connection is almost impossible: TCP uses random sequence number when negotiating the connection, and the attacker would need to guess the number, while not being able to see any reply from your API server. Spoof the domain would involve the attacker compromising the zone records for the ...


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I can think of VLAN with these 2 servers and ACLs to restrict traffic with any other server these may depend on. But depending on the specifics of your network and interactions, following might be applicable: iptable, micro segmentation. I recommend to read the 'Segmentation' chapter of Defensive Security Handbook.


2

How is it possible to change all the certificates? MITM (Man-in-the-middle). Your company is using some kind of proxy device that is intercepting all your requests and generates a certificate on the fly for the address you try to connect. The proxy basically acts like a CA, signing all the "fake" certificates performing MITM. Some vendors tend to call it ...


2

How is it possible to change all the certificates? The company is performing SSL inspection on the HTTPS traffic with a transparent proxy. This requires terminating the connection e.g. at the firewall and creating a new TLS connection for the client. This requires creating new (fake) certificates and signing it with an own CA. Why does my browser not ...


0

IP Spoofing, successful three way handshake (which used by TCP protocol) is not at everyone's fingertips. Yes TCP have security issues and also there is spoofing techniques but I believe your level of interest does not require that much attention. HTTP works over TCP. Would you want to have one of the following solution. If you are using a cloud provider, ...


0

Providing my comment as an answer since my reputation is to low for commenting. When using a SSL key log file it maps "identifiers" to master secrets. It tries to map by the following identifiers: Session ID ( that is the Session ID filed if a Server Hello handshake message) ClientRandom ( 32 bytes within the Random filed of a Client Hello handshake ...


0

The point of a firewall is that it creates a boundary between internal and external. Traffic going through the firewall passes from internal to external. So for all intents and purposes, consider the firewall to be wholly internal except for the 2-dimensional plane that is public-facing; in other words, the network is internal including the firewall up to ...


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There are a number of serverless client apps that you can tell your users to use. They don't redirect traffic, so there's no slowdown. You can use the Intra App on Android or GoodbyeDPI on Windows. It seems Green Tunnel works on Linux, Windows and macOS, but I never heard of it. Alternatively, you can host your site on Cloudflare, which supports encrypted ...


1

Lucky 13 applies to all cipher suites that use CBC, regardless of what else they use. The attack is solely against CBC and the way it's used in TLS, independently of what else the protocol does. There are several defenses against Lucky 13, but none of them is a panacea. In principle, Lucky 13 is an attack against implementations of TLS, not an attack on ...


0

At the bottom you will see return output_tab(cert), output_str(cert) this is the main code which calls the local functions. You want to edit output of output_str function so change the call as output_str(cert, host, port) and local function output_str(cert, host, port) than it will work. For full example you can check following code. Replace source code ...


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