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+--- Thread: Cracking a CHAP from Freeradius (/thread-7287.html)
RE: Cracking a CHAP from Freeradius - undeath - 02-12-2018
Go to https://hashcat.net/wiki/doku.php?id=example_hashes and search for "chap". Should clear up your questions. I also recommend taking a look at the output of hashcat --help
RE: Cracking a CHAP from Freeradius - honeyfairy - 02-12-2018
(02-11-2018, 02:05 AM)ZerBea Wrote: I do not want capture this thread, but I have a question:
Do you have some informations about (free)RADIUS, specifically about the packet structure of the Attribute Value Pairs in the Access-Request Packet [User-Password encrypted(2) or CHAP-Password(3)].
I know this Password is encrypted using a MD5 chiffre (MD5 xor Password). The MD5 is calculated from secret share+random Authenticator - but i don't have any ideas about this secret share. Also I know the rfc2865 document.
We have this both fields (Authenticator and encrypted User Password) in an Access-Request Packet (and additionally a HMAC_MD5 over the complete Access-Request Packet).
I do not need an answer anymore as I found it:
A note on security: The security of the RADIUS protocol
depends COMPLETELY on this secret! We recommend using a
shared secret that is composed of:
- upper case letters
- lower case letters
- numbers
And is at LEAST 8 characters long, preferably 16 characters in
length. The secret MUST be random, and should not be words,
phrase, or anything else that is recognisable.
The default secret below is only for testing, and should
not be used in any real environment.
secret = testing123
I do not understand completely.
1. How would an easy shared secret be used to compromise the radius?
2. If I set a 16 character shared secret, will the hashes be harder to crack?
PS: i'm [very] new to cryptography, but I AM enjoying myself with great guys like you!
RE: Cracking a CHAP from Freeradius - honeyfairy - 02-12-2018
If I understand correctly, the password hash cannot be cracked without the correct Challenge [salt] - Am I correct?
For example, if the RADIUS
RE: Cracking a CHAP from Freeradius - undeath - 02-12-2018
yes, the challenge is required in order to crack the hash.
RE: Cracking a CHAP from Freeradius - honeyfairy - 02-12-2018
If I understand correctly, the password hash cannot be cracked without the correct Challenge [salt] - Am I correct?
For example, if the RADIUS database has a user stored as follows:
Username: alishiazav
Password: honeyfairy
And If a user logs in with the following:
Username: alishiazav
Password: zavreski
Then, could the hash still be cracked using the method that we used, or not [due to the salt being incorrect]
Lastly, what is the ID at the end?
RE: Cracking a CHAP from Freeradius - undeath - 02-12-2018
I don't know how the CHAP handshake works but I would expect you can still crack a hash with a wrong password. The challenge should still be transmitted.
Unless it was coincidence the ID at the end is what is prepended to the "password" hash in your first post.
RE: Cracking a CHAP from Freeradius - ZerBea - 02-12-2018
We are talking about different things.
You can crack a RADIUS password with hashmode -m 4800 (CHAP). But that's only one single variant.
For example: sometimes the password is stored as BASE64(SHA1(password)) in the database of the server.
My question relates to the transport layer (packet layer of IP communication) between the client and the server.
Right now we are able to crack 2 variants (LEAP-CHAP[PPP], MD-5 challenge[EAP]). During my packet analysis I found 3 other variants (PAP, CHAP, MD5), we are not able to crack.
For your example above:
Username: alishiazav
Password: zavreski
secret share=29495ade5d6f88f1
The client build an access-request packet and sends this to the server. This packets contains
- an authenticator (random generated),
- the encrypted user password: MD5 chiffre = key xor zavreski, the key is calculated MD5(29495ade5d6f88f1+authenticator)
- and a HMAC_MD5 calculated over the packet
The server responds to the request with an access-accept packet.
Goal is to retrieve the password, if we captured this access-request packet.
RE: Cracking a CHAP from Freeradius - honeyfairy - 02-12-2018
(02-12-2018, 01:13 AM)undeath Wrote: I don't know how the CHAP handshake works but I would expect you can still crack a hash with a wrong password. The challenge should still be transmitted.
Unless it was coincidence the ID at the end is what is prepended to the "password" hash in your first post.
Thank you for the info. I checked the link you gave me. I understand now. Just one more question, how did you know that the ID is the first two digits after 0x? I could not find this info.
RE: Cracking a CHAP from Freeradius - undeath - 02-12-2018
trial and error + educated guessing
RE: Cracking a CHAP from Freeradius - honeyfairy - 02-12-2018
(02-12-2018, 02:49 PM)undeath Wrote: trial and error + educated guessing
Now I need a Guru mentor like this. Could you give me some links so that I could also learn abit and educate myself on this. Otherwise I'll have to come to undeath to guess for me