BS Level 10: Next Level Challenges
BSides wouldn't be BSides without challenges!
Challenges will be released on a not-so semi-regular schedule; visit this page regularly to catch one.
Do you think you have what it takes to hack your way through, learn somthing new and possibly win one of a number of those rare tickets to the event? or one of those most excellent prizes from our Sponsors?
Go forth, hack, and send us you writeup!
How to Play and Level UP:
- All submissions are to be submitted as per the challenge instructions.
- Submissions must be sent in by 27
MAYSEPTEMBER 2020 or the date listed on the challenge page. - Hints are only available if the creator
deems you worthyprovides them. - Hints can be requested via the challenges team email: ctfs2020 [@] securitybsides[.]org[.]uk.
- The challenge creator is the boss, s/he decides the best winner.
- Prizes will be awarded on the day, except for the tickets etc.
Note there are two ways to win for most challenges: fastest to submit and best writeup of the solution.
The BSidesLondon Team wants to thank all those who helped with the challenges and the fantastic prizes.
Crack me if you can:
What's the response to the Arecibo Message?
The Jodrell Bank Observatory received a message that originates from M13. It appears to be a reply to the Arecibo Message. Unfortunately, the received message is corrupt: a single bit was flipped somewhere at the start of a data chunk. It is your mission to decode the message.
Instructions
The PNG file's MD5 is 6a505a33fcf5777e240b0cd2ab4b5c91
Please read the message carefully.
.
This challenge has been completed/won.
We are pleased to present this challenge courtesy of the ever inventive and long time provider of challenges to BSides London Didier Stevens. If you have not already heard of him, you should take a few moments to check out his excellent blog, where you can find a dizzying array of analysis tools, tips, and tricks.
MBRland
Your Windows PC has been ransomwared using the newly found CVE-2020-0796. The malware overwrote your MBR boot sector and now wants you to enter a password with which it will decrypt the files. Recover the password and save your files!
The boot-sector is executable in QEMU:
qemu-system-x86_64 -hdd boot.bin
Download the boot.bin file here 
Instructions
The boot.bin file's SHA256 is 36317cf72af2bd68f63e7f8e0b07b3a193daa03ebe13ed748cd8b73507240928
.
This challenge has been completed/won.
Many thanks to Jan Neduchal for providing this challenge.
Denominate
(medium difficulty)Our client's network has been compromised, so we captured some traffic for analysis, can you find out what attacker did inside his network?
The file capture is available to download here 
Instructions
Download the forensics_denominate.zip file's SHA256 is 8e4ed9c3c2e566d49d6fe7bb23a10752397b6bed666100feca4588574285896e
You will need to convert extracted RTP stream to `.wav` and detect DTMF Tones. The flag is a string of numbers, the `HTB{}` prefix should be added before submitting.
This challenge has been completed/won.
Many thanks to Hack The Box for providing this challenge.
Surprise
(medium difficulty)Here's a small gift for you! Can you unpack it though?
The gift is available to download here
Instructions
Download the Challenge4_rev_surprise.zip file's SHA256 is 539f67db76458cadc7d1e1b6a31223f459f1d817e29c41ebbd6179633bf69699
Reversing a binary with encrypted code segments; find the flag. The flag is a string of numbers, the `HTB{}` prefix should be added before submitting.
This challenge has been completed/won.
Many thanks to Hack The Box for providing this challenge.
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