Is it possible for corporation to intercept and decrypt SSL/TLS traffic? [duplicate]

Question

I found there are some companies claim that they offer service that can eliminate SSL/TLS blind spot, such as Blue Coat and Gigamon. Are they talking about some way of decipher the https content (breaking the encrypting algorithms) or just man-in-the-middle attack ? If it is a MITM proxy, can I simply detect it by checking the CA of the certificate installed on my browser?

My question is about whether there is way to monitor https traffic without MITM attack and whether it is possible for MITM proxy to dupe users by showing certificates with real CAs (DigiCert, Comodo) so I cannot just tell the difference by looking at the CA.

Answer 1

Installing a root certificate on users browsers, and conducting a MiTM attack on employees is unfortunately a standard practice at many companies.

There's a few ways you can detect this.

1. One way is looking for a root CA cert installed on your computer and see if you don't recognize one of the CAs. This of course requires an in-depth knowledge of what real root CAs are, and what fake MitM proxy providers are.

2. Another is simply looking at the certificate an https websites generates and examine who it's signed by. The cert of all https sites will be signed by the company providing the MiTM attack proxy.

3. A third way is to install Firefox, preferably a version that doesn't install and runs as a standalone. Firefox doesn't use the system provided certs, but uses its own certs. You can get this from http://portableapps.com/ If you then get a security warning about a self signed certificate, you're being MiTMed by your company.

Answer 2

It's pretty clear that they aren't able to decrypt any encrypted traffic for which they're not in possession of encryption key. They are more likely doing it like mitmproxy does; They might deploy their root certificate to all clients of a company by group policies for example, and are then able to replace all certificates of web servers,... on their own because they are now considered a trusted CA (Certificate Authority) in all web clients.

This would allow them to decrypt all connections which are encrypted based on any certificate in the certificate chain issued by their own root CA. This technique is also used by some anti virus software.

This won't work with symmetric encryption with a PSK (Phase-Shift Keying), of course.

Answer 3

Blue Coat: How to Gain Visibility and Control of Encrypted SSL Web Sessions :

Because a proxy is an active device (i.e., it terminates traffic), it acts as both the server to the client, and the client to the server. Thus, it has a native understanding of both the user and the application. For many organizations, users will only connect to the Internet via a proxy – because of the control it affords an enterprise. Because a proxy terminates connections, it offers a critically important control point for policy, performance, and protection of all Web-enabled user and application interactions.

Blue Coat SG is the leading secure proxy appliance, offering enterprises “the power of the proxy” in a broad range of sizes. Blue Coat extends that leadership by offering SSL proxy functionality on its market-leading proxy appliance.

Whereas takes an other approach -decryption: ( Giamon: SSL Decryption: Uncovering The New Infrastructure Blind Spot)

The offloading of SSL decryption also eliminates the need to have multiple decryption licenses for multiple tools. After all, a security appliance with integrated SSL decryption, for example, does not benefit other tools, such as application performance monitoring. Gigamon can supply decrypted traffic to multiple tools simultaneously, maximizing the overall efficiency, security, and performance of the infrastructure. An associated benefit of this approach is that the private keys can now be securely uploaded to just the visibility infrastructure instead of sharing it with multiple tools.

It also delivers to IT and security administrators the right level of visibility into traffic, including SSL-encrypted segments that are at the heart of today’s cloud infrastructures.

GigaSMART decrypts the packets and sends the traffic to multiple out-of-band tools, including intrusion detection (IDS), data loss prevention, and application performance monitoring for analysis.

Answer 4

So there are 4 common vulnerabilities in SSL that immediately come to mind:

1. Install a root certificate on your computer that allows the interceptor to be an SSL authority and create forged SSL certificates. This requires them to have administrative access to your computer, even still the SSL fingerprints will be different.
2. Do a MITM attack on non-SSL sites then use SSL Stripping when connecting to SSL sites. HSTS (Strict Transport Security) can help mitigate this by caching for a period of time that the site uses a secure connection (and not allowing insecure connections for this period of time).
3. Where the SSL configuration is improperly set-up, this can be seen by running the site through an SSL Labs test and noting the vulnerabilities. This can include using weak ciphers, weak key exchange or using outdated SSL protocols instead of going through TLS.
4. The hashing algorithm on the certificate also plays a major part in keep SSLs secure, hence why Chrome is phasing out SHA1.

Answer 5

No, noone can break 2048-RSA certificates yet that are commonly used - not enough computing power.

However your browser can be tricked via another (fake) certificate. It's very similar to how Fiddle works to view encrypted traffic (Fiddle is a network activity analyzer)

1. First Fiddler creates & installs a trusted root certificate.

2. You browse https://www.googole.com

3. Fiddler creates a (fake) certificate for Google and signs it with the certificate from step 1.

4. Fiddler intercepts all traffic from you to google and back (and the portion of the traffic between you and Fiddler is signed with the fake certificate). Your browser is duped into thinking the fake certificate is OK and you suspect nothing.

A neat trick.

However you can easily smell a rat if you look at the signing authority of the site's certificate and seeing that it's not one of the recognized brands (Thawte, VeriSign, etc)

Answer 6

Also bear in mind that nextgen Security Appliances like those from Palo Alto and Huawei USG firewalls, have this functionality baked-in. This is ostensibly to deal with the "blind spot" in which because outbound SSL is typically allowed, can be used by employees to circumvent security (shocking I know). By decrypting the SSL, appliance can perform application-based filtering,