Hack.lu 2015: Creative Cheating

Write-up of Hack.lu 2015’s Creative Cheating challenge.

The first challenge I solved on Hack.lu 2015, hosted by FluxFingers, was Creative Cheating.

The challenge

Mr. Miller suspects that some of his students are cheating in an automated computer test. He captured some traffic between crypto nerds Alice and Bob. It looks mostly like garbage but maybe you can figure something out. He knows that Alice’s RSA key is (n, e) = (0x53a121a11e36d7a84dde3f5d73cf, 0x10001) ( and Bob’s is (n, e) = (0x99122e61dc7bede74711185598c7, 0x10001) (

The solution

Upon inspection of the packet capture, we notice every packet from Alice ( to Bob ( contains a base64-encoded payload. E.g.


Continue reading

How to set up a Wifi captive portal


The objective of this Wifi captive portal is to mimic the behaviour of a legitimate access point protected by a portal login page for demonstrational purposes. That includes the following:

  • Broadcast a rogue access point
  • Mimic captive portal behaviour:
    • User gets to see a login page when trying to connect;
    • After logging in, the user can continue to access the network and surf freely.

Continue reading

CSRF Discoverer – A Chrome extension

Continue reading

HTTP Auth Phishing

HTTP Auth offers attackers easy phishing. This post describes how it is done and how the attacker could circumvent the constant reappearing of the authentication prompt.


An attacker could force an HTTP authentication pop-up window in the victim’s browser and log the input to a file on his own server. This post is the write-up of an idea I had a while ago. While investigating, I found out the idea had been coined before. Find some related posts below my findings.

This attack doesn’t require much work from the attacker. Let’s have a look at some of the configuration he needs.

Continue reading