237 votes
Accepted

Is there anything preventing the NSA from becoming a root CA?

It is already done: It is the FPKI root CA, under explicit and full control of the US government. Windows already trusts it by default. Before you flip out and begin to delete root CA certificates, ...
user avatar
89 votes
Accepted

Is there a way to make sure my government does not swap out SSL certificates?

If your adversary is a powerful nation-state threat actor, web PKI will not protect you. Nothing is preventing them from issuing their own certificate. In fact, many governments run their own ...
user avatar
  • 64.1k
83 votes
Accepted

How can my employer be a man-in-the-middle when I connect to Gmail?

You are absolutely correct in your assumptions. If you are using a computer owned and operated by your employer, they effectively have full control over your communications. Based on what you have ...
user avatar
  • 5,464
78 votes
Accepted

Why is Firefox (and only Firefox) reporting that my connection is insecure on multiple sites?

There is a lot to unpack so I’ll do my best here (based on some assumptions). Firefox maintains its own certificate store which is likely the reason only Firefox is throwing these errors. ...
user avatar
  • 9,227
78 votes
Accepted

How can Kazakhstan perform MITM attacks on all HTTPS traffic?

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 ...
user avatar
73 votes
Accepted

Why is SMS used as a way of verifying a user's mobile, when it is not even encrypted in transit?

Yes, you're right. SMSes are not recommended in any two-factor authentication (2FA) process nowadays. They can be easily intercepted and modified. That's why a lot of companies are recommending other ...
user avatar
  • 1,404
72 votes

Are all these attacks possible with WiFi MitM or is it over-hyped nonsense?

Am I missing something, or does this community concur that this video is either over-simplified or just plain deceitful. I wouldn't say it's deceitful, but it's definitely overhyped/oversimplified. ...
user avatar
  • 3,699
69 votes
Accepted

Is receiving fake torrent data possible?

Yes, a client will notice and block. A torrent is divided into pieces, a piece is divided into chunks. Every piece has its SHA1 hash included in the .torrents metadata. If a peer send fake or ...
user avatar
  • 589
68 votes
Accepted

Why aren't IMSI catchers rendered ineffective by standard MITM defenses?

tl;dr - the protocols were developed prior to MITM being perceived as a threat; the deployed infrastructure now serving billions of cell phones worldwide can't easily be changed to add cell tower ...
user avatar
  • 33.6k
66 votes
Accepted

Is it common practice for companies to MITM HTTPS traffic?

Is this common practice in big companies? Yes. The feature is available in most enterprise firewalls and also several firewalls for smaller companies. It is even available in the free web proxy Squid....
user avatar
63 votes
Accepted

Can or should whitelisting replace encryption?

The sniffing problem is about "confidentiality", which whitelisting does not cover, as the traffic can be intercepted and read. The MitM problem is about "authenticity", which whitelisting does not ...
user avatar
  • 13k
63 votes
Accepted

Is there such a thing as a "Black Box" that decrypts Internet traffic?

Yes. It's called a Man-in-the-Middle attack. You terminate the SSL session at a mid-point, thereby having the encryption key, then create a new session to the target server, so you have that ...
user avatar
  • 27.2k
62 votes
Accepted

How does one take advantage of unencrypted traffic?

You can trust your ISP, but your data will not pass through just your ISP's routers. On a simple level, the internet works by passing data from one router to another, repeatedly moving each packet ...
user avatar
  • 10.8k
61 votes
Accepted

How to verify the checksum of a downloaded file (pgp, sha, etc.)?

Usually this would start on the owners side displaying the checksum for the file that you wish to download. Which would look something like the following: md5: ba411cafee2f0f702572369da0b765e2 ...
user avatar
  • 1,444
59 votes
Accepted

What stops someone from just redirecting a HTTPS connection to a HTTP version of the site?

The decision on whether to use HTTP or HTTPS is the client's. If the user goes directly to http://example.com, an attacker could simply hijack that connection and perform a man-in-the-middle attack. ...
user avatar
  • 132k
59 votes

Why is the HTTP protocol more susceptible to being intercepted than the BitTorrent protocol?

The difference is that the BitTorrent protocol has a mechanism to verify that you received what you intended to receive, whereas HTTP does not. HTTP has no mechanism... to verify that you are ...
user avatar
  • 1,108
55 votes

Is there anything preventing the NSA from becoming a root CA?

The NSA could and probably already has gone -- using a USA PATRIOT Act demand letter, or other similar legislative tool -- to all the major CAs in the United States (e.g. VeriSign, GeoTrust, etc.) and ...
user avatar
  • 800
55 votes

Why are SSH MITM tools able to read and modify data?

The basic point of a MITM attack against SSH or SSL/TLS is that the connection is no longer end-to-end encrypted, i.e. from client to server. Instead there is an encrypted connection between client ...
user avatar
52 votes

Why is SMS used as a way of verifying a user's mobile, when it is not even encrypted in transit?

SMS is not exactly plaintext. The network operator has it in plaintext, but the attack surface there is limited and both organizational and technological measures limit the exposure. Over the air, it ...
user avatar
  • 3,385
51 votes

Why do browsers allow custom root CAs?

As pointed out in comments and answers, there are plenty of legitimate reasons why you would want to add a CA to your browser's trust store, and the mechanisms for doing this require admin access to ...
user avatar
50 votes
Accepted

For an HTTPS web application, is it worthwhile to encrypt the password before POSTing it, to keep a MITM attacker from harversting it?

This recommendation makes no sense: The JavaScript code used to hash or encrypt the password has to be transferred to the client too. If the attacker is able to mount a man-in-the-middle attack he ...
user avatar
49 votes
Accepted

Is it possible for a name server provider to hijack MX records?

Yes, your registrar can hijack not only your MX records, but your entire DNS. Not only that - but they can then proceed to intercept mail sent to your domain, get a valid CA-signed SSL certificate ...
user avatar
  • 19.8k
47 votes
Accepted

Why are some websites seemingly immune to self-signed certificate MitM attacks?

Facebook uses HSTS (with preload[*]) while steamcommunity.com doesn't. HTTP Strict Transport Security is a HTTP header that has two effects: It forces all connections to the site over HTTPS (even ...
user avatar
  • 29k
44 votes
Accepted

Can attackers change the public key of certificate during the SSL handshake

... 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 ...
user avatar
43 votes
Accepted

Possibility to sniff HTTPS traffic on devices without installing a certificate

The entire point of SSL is its resistance to eavesdropping by man-in-the-middle attacks like the one you're proposing. If you cannot make the client device trust your self-signed certificate, then ...
user avatar
  • 5,780
42 votes
Accepted

Why can't a hacker just obtain a new SSL certificate for your website?

Being able to MitM a certificate authority is perhaps not as trivial as you imagine. You don't know what machine they're using to evaluate ownership, and hopefully they aren't doing this over ...
user avatar
41 votes

Why is there no web client for Signal?

Yes HTTPS is used. The thread doesn't say that the web app will be completely insecure, instead it says This effectively reduces the security of your end-to-end encrypted communication to that of ...
user avatar
  • 10.8k
40 votes

Superfish vs. Corporate MITM

What makes Superfish, and similar products (all herein just referred to as "Superfish"), different from corporate MitM is that Superfish is doing the MitM on the client machine. Corporate MitM is ...
user avatar
  • 27k
40 votes

Are all these attacks possible with WiFi MitM or is it over-hyped nonsense?

All the attacks are possible and not over-hyped. In fact, these attacks are found in the wild. But you missed a detail that makes your conclusions incorrect. There are some steps that the attacker ...
user avatar
  • 123k

Only top scored, non community-wiki answers of a minimum length are eligible