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Hacking techniques include penetration testing, network security, reverse cracking, malware analysis, vulnerability exploitation, encryption cracking, social engineering, etc., used to identify and fix security flaws in systems.

Claymore’s Dual GPU Miner 10.5 and below is vulnerable to a format strings vulnerability. This allows an unauthenticated attacker to read memory addresses, or immediately terminate the mining process causing a denial of service.

After reading about the recent vulnerabilities with previous versions, I thought I should take another look at the json listener on port 3333 and see if there was any avenues of attack.

echo -e '{"id":1,"jsonrpc":"1.0","method":"test"}' | nc 192.168.1.107 3333 & printf "\n"

After realizing the buffer was printed I decided to try a few others…

Sending %s does return some strings, however I couldn’t get the hex addresses padded properly to dig in more as I kept getting unable to parse json errors. Sending %p also did yield some results but I’m sure someone more qualified may be able to exploit the stack further…

Finally, sending %n completely kills the mining process.

echo -e '{"id":1,"jsonrpc":"1.0","method":"%n"}' | nc 192.168.1.139 3333 & printf "\n"

Keep your rigs up to date, or stop opening port 3333 to the public. Seriously.

Timeline
01/26/18 — Reported

01/26/18 —Confirmed and immediately patched. 10.6 released request for 3–4 day embargo

01/31/18 — Public Disclosure