HACKvent 2017 write-up


Like every year before Christmas the HACKvent is on! It is a Jeopardy CTF competition in the style of an advent calendar. Every day at 00:00 a new challenge is released. It starts with easy ones and then becomes harder and harder. If you solve a challenge before the next one is released, you’ll get full points. Oh boy, the last couple of days were stressful…

Unfortunately I lost 1 point because I wasn’t able to submit the tamagotchi challenge on time. It was even more frustrating when I’ve found out, that it didn’t work because of a copy/paste error.

Nevertheless, I am very happy with the result as I still managed to finish on the 8th place! 🙂

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HackyEaster 2017 write-up

Easter 2017 – means new HackyEaster challenges are online. The challenges were easier than the ones on Hackvent 2016. For HackyEaster all challenges are released at once and it does not matter in what time-frame the challenges are solved, this makes the CTF much less stressful than Hackvent. I solved my last challenge on April 16th at 01:24 AM and completed the CTF after eleven others did before me. Here is a screenshot of the ranking at the time I finished the last challenge.

After the competition ended in total 53 hackers solved all challenges and got the full points.
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HACKvent 2016 write-up

Update 06.01.2017: Added the challenge descriptions. Thanks to khr0x40sh!

HACKvent is a CTF competition provided by Hacking-Lab.com. During advent time every day a new challenge is released. The challenges get harder every day and full points are only given if they get solved within the same day.

I solved all challenges except the last one, but not always the same day though. I had no more time and strength to solve the last one on Christmas. The CTF was a lot of fun but very stressful next to my job.

I ended on rank #23.

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Auto brightness on stock Android (ICS or earlier)

Recently I stumbled across Androids auto brightness feature/bug. On all Android phones I ever possessed, the auto brightness was working as expected. When you enter a brighter area the display gets brighter. Returning back to a darker zone the display gets dimmed. On my own AOSP(Android Open Source Project)-build my phone display never got dimmed. When a certain brightness level was reached the display stayed on this level, even if I covered the light sensor. The brightness remained so until the phone got locked and/or the phone display went off. I tested this behavior on three Google phones: Nexus One, Nexus S and on the Galaxy Nexus. On other phones I could not reproduce this. All phones I’ve tested were on their original software. The fact detecting this on Google phones (AOSP builds) but not on others tells me that many phone providers (e.g. Samsung) are not happy with it and changed this behavior by themselves. Continue reading

Pictures appearing multiple times – ICS

A few weeks ago I installed the new Android 4.0 – “Ice Cream Sandwich” on my Samsung Galaxy SII. There is no stable version yet so I took the experimental build of CyanogenMod 9. You’ll find the latest ROM here.

After using it for few days, maybe I did an upgrade to a newer version – can’t remember, the pictures in my albums appeared twice or more… I deleted the data of the gallery app, I manually checked the data of the gallery app with adb and I searched for .thumbnails and deleted them all. None of all these steps worked. Continue reading

Android Gallery app – Pictures order

A few weeks ago I bought a new Android phone, the Samsung Galaxy S2 to be precise. On my old cell I took a lot of pictures and I wanted to transfer them to the new phone. In order to do so, I backed up the camera folder /mnt/sdcard/DCIM/Camera to my computer and afterwards I copied it to the new phone. So far so good.

However, as soon as I looked at the pictures in the Gallery app it occurred to me that they were not chronologically ordered anymore. I found out that the Gallery app is sorting the pictures by the time stamps of the files. During the copy process all the timestamps of the photos have been lost. Continue reading

Sudo insult mode

Insult mode is a funny sudo feature:  Whenever you enter a wrong password sudo insults you.

For enabling the insult mode open the /etc/sudoers file as root and type “insults” at the end of the ‘Defaults’ line. The tags in the ‘Defaults’ line are comma separated. If there is no ‘Defaults’ in your config just write “Defaults insults” to your /etc/sudoers.

Just enter a wrong password when using sudo and see what happens.

Gnome 3 – Change the message notification duration

Recently at work I updated my box to Ubuntu 11.04. I really couldn’t handle Unity – so I installed Gnome 3… It took some time but now I like it.

I have pidgin installed and every chat message I get shows me a Gnome message notification for a couple of seconds. A nice, useful helper I would say. But I’m at work and some friends of mine have the terrible habit to write a new message for every single word they use. 🙂 When someone is starring at your screen at this time it’s quite uncomfortable…

After googling a bit I couldn’t find any solution to change the duration time of the notification. So I’ve found a solution on my own. I tested this on Ubuntu 11.04 and on my Arch Linux computer at home. Continue reading