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Cryptographic splicing makes for a Wordpress vulnerabilityCryptographic splicing makes for a Wordpress vulnerabilityPosted May 9, 2008 16:47 UTC (Fri) by giraffedata (subscriber, #1954)In reply to: Cryptographic splicing makes for a Wordpress vulnerability by eru Parent article: Cryptographic splicing makes for a Wordpress vulnerability
The explanation misses a lot of details. I'm wondering how the hacker makes the expiration string "bar20080507". Does the client choose the expiration string? That seems like something the server would do. Also, the article doesn't really explain what an authentication cookie is, but I presume it's something the server sends to a client that has provided a valid password so that knowing that cookie in the future can stand for knowing the password. And for some reason that's better than just having the password as a cookie.
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Cryptographic splicing makes for a Wordpress vulnerability Posted May 16, 2008 12:15 UTC (Fri) by robbe (guest, #16131) [Link]
> The explanation misses a lot of details.
Here's my understanding (only from the article, YMMV):
0. Assume that there is an "admin" account with special power, and that
the attacker has created an "admin99" account.
1. The attacker successfully logs in via a form, and the server sends her
the cookie "admin99|20080601|DEADBEEF". (Assume that md5
("admin9920080601secret") == "DEADBEEF".)
2. On subsequent requests the attacker presents the above cookie. The
server notices that the cookie is valid (because md5
("admin9920080601secret") == "DEADBEEF"), that this is user "admin99",
and that the session has not yet expired (it's still May 2008). Fine!
3. But now the attacker sends the following doctored cookie: "admin|
9920080601|DEADBEEF". This still checks out as valid because md5
("admin9920080601secret") == "DEADBEEF"), the session is for some
reason[1] still not considered expired, so the attacker now has the
identity of user "admin".
[1] IMO not validating the expiration date format is one of the main
errors here. Or does WP strive to be Y10K compliant??
Cryptographic splicing makes for a Wordpress vulnerability Posted May 16, 2008 13:37 UTC (Fri) by jake (editor, #205) [Link] > IMO not validating the expiration date format is one of the main > errors here. Or does WP strive to be Y10K compliant?? In the article, I was trying to steer clear of providing complete, exploitable details while still giving more details than the advisory. I believe the expiration is actually the number of seconds since the epoch, which may be easier to exploit and still validate as a reasonable expiration. jake
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