Most servers like nginx, Apache, MySQL, and forks then communicate with the client. This means canary and addresses stay the same even if there is ASLR and PIE. So we can use some educated brute force to leak information and subsequently craft a working exploit.
Flow of exploitation
Find buffer overflow offset
Find canary
Find saved registers (RBP / RIP)
Find stop gadgets
Find brop gadgets
Find a Write function (write / dprintf / puts / …)
Leak the binary
Examples of Results
There are 3 customs vulnerable examples provided in this repository. You can run it directly or build the Dockerfile
BROPPER will then dump the binary :
It’s then possible to extract all ROP gadgets from the dumped binary using ROPgadget for example :
options:
-h, --help show this help message and exit
-t TARGET, --target TARGET
target url
-p PORT, --port PORT target port
--expected-stop EXPECTED_STOP
Expected response for the stop gadget
--expected EXPECTED Expected normal response
--wait WAIT String to wait before sending payload
-o OUTPUT, --output OUTPUT
File to write dumped remote binary
--offset OFFSET set a offset value
--canary CANARY set a canary value
--no-canary Use this argument if there is no stack canary protection
--rbp RBP set rbp address
--rip RIP set rip address
--stop STOP set stop gadget address
--brop BROP set brop gadget address
--plt PLT set plt address
--strcmp STRCMP set strcmp entry value
--elf ELF set elf address
