4 ms·
>> Also how do you as an attacker know that it was user not a e-mail server checking those images? > Agent signatures. Can you Expand? Googling isn't helping
by pbowyer 6y ago
>> Also how do you as an attacker know that it was user not a e-mail server checking those images?
> Agent signatures.
Can you Expand? Googling isn't helping me understand what this means/how it works.
- eganist 6y agoThe "user agent string" of the email client is different from that of the user's browser.
- chrisseaton 6y agoAlso called agent fingerprinting. You can look at exactly how the agent is responding and make educated guesses at what agent it is. You think one HTTP request looks like any other, but there's enough little bits of information here and there to leak info. The user agent is the simplest example. That can be spoofed, but there's more subtle traces as well, all the way down the stack https://en.wikipedia.org/wiki/TCP/IP_stack_fingerprinting https://en.wikipedia.org/wiki/TCP/IP_stack_fingerprinting.
- pbowyer 6y agoThanks!