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jebidiah-anthony

write-ups and what not

Space Challenge

PART 1 : GIVEN FILES

PART 2 : GETTING THE FLAG

The dump file contains all the data received by a CAN interface and the first thing I did was to clean up some noise from the log:

$ log_file=$(cat diwata_satellite_canbus_dump.log | tr '#' ' ')

$ echo "$log_file" | awk '$3!=300 && $3!=056 && $3!=050 { printf "%s %s\n", $3, $4 }' | sort | uniq

  123 DEAD1337
  123 DEADBEEF
  188 030000
  19B 00000F
  19B 000010
  202 6001606060606000
  244 0000009999
  400 7370
  401 616365736174656C
  402 6C69746573686176
  403 6563616E746F6F
  510 10AD013CF048120B
  600 021001
  7E0 0103
  7E0 0107
  7E0 020100
  7E0 020900
  7F1 0322F19000000000

The first column are CAN IDs and the second column is the unique data each ID contains.

Unusual data are found in CAN IDs — 123, 400, 401, 402, 403. And those with 40X IDs seem to contain lowercase ASCII characters (\x61 - \x7A).

$ echo "$log_file" | grep -e "^(.*) vcan0 40. .*$" | awk '{ printf $4 }'

  7370616365736174656C6C697465736861766563616E746F6F

$ echo 7370616365736174656C6C697465736861766563616E746F6F | xxd -p -r

  spacesatelliteshavecantoo

Extracting the hex string then converting it to ASCII gives us the flag!

FLAG : rc_easter{spacesatelliteshavecantoo}