hxp CTF 2021 hxp


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caBalS puking

by kirschju
misc crypto

Difficulty estimate: easy - easy

Points: round(1000 ยท min(1, 10 / (9 + [6 solves]))) = 667 points


Hey, did you hear the good news? We were finally able to get ADB access to kirschju’s phone. All we could find on the file system were two Signal backup files, though. Nevertheless, with hxp’s ever-delayed challenge development process, there is hope that we might find a flag in the backup.

The first backup coincides closely with the registration time of the target Signal account, so we believe it represents the state of an empty account. The second backup file is a lot larger, for sure there’s some valuable piece of information in there.

We’re also attaching the Signal app retrieved from the phone for your reference, but it doesn’t seem to be modified compared to a vanilla app.


caBalS puking-2672391a1b33417f.tar.xz (65.0 MiB)


CTFtime Logo CTFtime: Task & Writeups

Solved by:

# Team Time
caBalS puking released 2021-12-18 10:45:09 +0000 UTC
๐Ÿฅ‡ More Smoked Leet Chicken 2021-12-19 00:54:08 +0000 UTC
๐Ÿฅˆ copy 2021-12-19 02:45:13 +0000 UTC
๐Ÿฅ‰ STT 2021-12-19 03:44:02 +0000 UTC
4 Kalmarunionen 2021-12-19 11:13:33 +0000 UTC
5 t_firmware_section 2021-12-19 13:35:43 +0000 UTC
6 Super Guesser 2021-12-19 14:21:49 +0000 UTC