ASIS Quals 2017 – unsecure ASIS sub-d – 132 points

Description:
ASIS has many insecure sub-domains, but we think they are over HTTPS and attackers can’t leak the private data, what do you think?

Here is the pcap file.

This pcap shows the traffic of https protocol.

After filter with “ssl.handshake.certificate”, i got 101 different certificates. Extract those certificates by a script. Then use openssl to get the modulus. Check gcd of those modulus one-by-one, we got the common prime of the 1st modulus and the 99th modulus.

Then, we can factor them and create a private key file then import to wireshark to decrypt the traffic. Open wireshark –> edit –> preferences –>SSL –> edit RSA key lists then add 2 private key files obove.

File –> export objects –> HTTP to export flag.