While attacking unencrypted HTTP traffic can be done without having to deal with X.509 certificates and certificate authoritiesFrom (CA), SSL-encrypted HTTPS connections encrypt every request and response between client and server end-to-end. And because the transferred data is encryptedPhilipp C. Heckel's tech blog with a shared secret, a middle man (or a proxy) cannot decipher the exchanged data packets. When the client opens an SSL/TLS connection to the secure web server, it verifies the server’s identity by checking two conditions: First, it checks whether its certificate was signed by a CA known to the client. And second, it makes sure that the common name (CN, alsosome light edits: host name) of the server matches the one it connects to. If both conditions are true, the client assumes the connection is secure.
In order to be able to sniff into the connection, Proxy server can act as a certificate authority, however, not a very trustworthy one: Instead of issuing certificates to actual persons or organizations, proxy dynamically generates certificates to whatever hostname is needed for a connection. If, for instance, a client wants to connect to https://www.facebook.com, proxy generates a certificate for “www.facebook.com” and signs it with its own CA. Provided that the client trusts this CA, both of the above mentioned conditions are true (trusted CA, same CN) — meaning that the client believes that the proxy server is in fact “www.facebook.com”. The figure below shows the request/response flow for this scenario. This mechanism is called transparent HTTPS proxying.
While attacking unencrypted HTTP traffic can be done without having to deal with X.509 certificates and certificate authorities (CA), SSL-encrypted HTTPS connections encrypt every request and response between client and server end-to-end. And because the transferred data is encrypted with a shared secret, a middle man (or a proxy) cannot decipher the exchanged data packets. When the client opens an SSL/TLS connection to the secure web server, it verifies the server’s identity by checking two conditions: First, it checks whether its certificate was signed by a CA known to the client. And second, it makes sure that the common name (CN, also: host name) of the server matches the one it connects to. If both conditions are true, the client assumes the connection is secure.
In order to be able to sniff into the connection, Proxy server can act as a certificate authority, however, not a very trustworthy one: Instead of issuing certificates to actual persons or organizations, proxy dynamically generates certificates to whatever hostname is needed for a connection. If, for instance, a client wants to connect to https://www.facebook.com, proxy generates a certificate for “www.facebook.com” and signs it with its own CA. Provided that the client trusts this CA, both of the above mentioned conditions are true (trusted CA, same CN) — meaning that the client believes that the proxy server is in fact “www.facebook.com”. The figure below shows the request/response flow for this scenario. This mechanism is called transparent HTTPS proxying.
For this attack to work, there are a few conditions that must be met:
- Proxy server as standard gateway (HTTP and HTTPS): For both HTTP and HTTPS proxying, the proxy server must of course be able to intercept the IP packets — meaning that it must be somewhere along the way of the packet path. The easiest way to achieve this is to change the default gateway in the client device to the Proxy server address.
- Trusted Proxy CA (HTTPS only): For the HTTPS proxying to work, the client must know (and trust!) the proxy CA, i.e. the CA key file must be added to the trust store of the client.
For this attack to work, there are a few conditions that must be met:
- Proxy server as standard gateway (HTTP and HTTPS): For both HTTP and HTTPS proxying, the proxy server must of course be able to intercept the IP packets — meaning that it must be somewhere along the way of the packet path. The easiest way to achieve this is to change the default gateway in the client device to the Proxy server address.
- Trusted Proxy CA (HTTPS only): For the HTTPS proxying to work, the client must know (and trust!) the proxy CA, i.e. the CA key file must be added to the trust store of the client.
If you’re interested in transparently sniffing plain SSL sockets, you might want to try SSLsplit, a transparent TLS/SSL man-in-the-middle proxy. There are many ways to attack SSL, but you don't need fake SSL certificates, a rogue Certification Authority (CA), or variations on security expert Moxie Marlinspike's man-in-the-middle SSL attacks. Why go to all that trouble when you can just buy a SSL interception proxy, such as Blue Coat Systems' ProxySG or their recently acquired Netronome SSL appliance to do the job for you?
If you’re interested in transparently sniffing plain SSL sockets, you might want to tryFrom SSLsplit, a transparent TLS/SSL man-in-the-middle proxy. There are many ways to attack SSL, but you don't need fake SSL certificates, a rogue Certification AuthoritySteven J. Vaughan-Nichols on ZDNet (CAexcerpted), or variations on security expert Moxie Marlinspike's man-in-the-middle SSL attacks. Why go to all that trouble when you can just buy a SSL interception proxy, such as Blue Coat Systems' ProxySG or their recently acquired Netronome SSL appliance to do the job for you?
Blue Coat, the biggest name in the SSL interception business, is far from the only one offering SSL interception and breaking in a box. Until recently, for example, Microsoft would sell you a program, Forefront Threat Management Gateway 2010, which could do the job for you as well. With an SSL interception proxy program or device in place, here's what really happens:
Blue Coat, the biggest name in the SSL interception business, is far from the only one offering SSL interception and breaking in a box. Until recently, for example, Microsoft would sell you a program, Forefront Threat Management Gateway 2010, which could do the job for you as well. With an SSL interception proxy program or device in place, here's what really happens:
If your company has set up the proxy correctly you won't know anything is off because they'll have arranged to have the proxy's internal SSL certificate registered on your machine as a valid certificate. If not, you'll receive a pop-up error message, which, if you click on to continue, will accept the "fake" digital certificate. In either case, you get a secure connection to the proxy, it gets a secure connection to the outside site -- and everything sent over the proxy can be read in plain text. Whoops.
If your company has set up the proxy correctly you won't know anything is off because they'll have arranged to have the proxy's internal SSL certificate registered on your machine as a valid certificate. If not, you'll receive a pop-up error message, which, if you click on to continue, will accept the "fake" digital certificate. In either case, you get a secure connection to the proxy, it gets a secure connection to the outside site -- and everything sent over the proxy can be read in plain text. Whoops.
