writeups

Writeups - Forensic - BusyBee

noraj (Alexandre ZANNI)
, , ,
🇬🇧

Information#

Version#

Date By Version Comment
05/06/2016 noraj 1.0 Creation

CTF#

Name#

BusyBee

Category#

Forensic

Wording#

A deadly virus is killing bees in Busybee's village Busybox, India. Unfortuantely, you have to go to the village to fight the infection. Get the flag virus out of the infected files. Village address: http://hack.bckdr.in/BUSYBEE/infected.tar Created by: Ashish Chaudhary

Data(s)#

link

Solution#

Methodology#

  1. Untar the datas: tar xaf infected.tar
  2. List the content of the directory:
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ls -AgG
total 2332
drwxr-xr-x 2    4096 Jun  3 18:13 2b0fbc0e1ac044737fd881cff8164bb5a2c7bfbf90c40c87de3c3435f2c6a94e
drwxr-xr-x 4    4096 Jul  2 19:01 983179bdb58ea980ec1fe7c45f63571d49b140bdd629f234be9c00a6edd8a4a7
drwxr-xr-x 2    4096 Jun  3 18:13 d51a083a3b01fe8c58086903595b91fc975de59a9e9ececec755df384a181026
-rw-r--r-- 1    1344 Jun  3 18:13 eaa21323de5e2cce7078df3af4dd292181114dfc94be761b948657efbe3af26b.json
-rw-r--r-- 1 2362880 Jun  6 08:17 infected.tar
-rw-r--r-- 1     373 Jan  1  1970 manifest.json
-rw-r--r-- 1     106 Jan  1  1970 repositories
  1. Display repositories file, it looks interesting:
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cat repositories
{"busybox-1.24.1-infected":{"latest":"983179bdb58ea980ec1fe7c45f63571d49b140bdd629f234be9c00a6edd8a4a7"}}
  1. 983179bdb58ea980ec1fe7c45f63571d49b140bdd629f234be9c00a6edd8a4a7: show us which folder is infected, so display its content:
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ls -AgG 983179bdb58ea980ec1fe7c45f63571d49b140bdd629f234be9c00a6edd8a4a7/
total 1020
-rw-r--r-- 1       3 Jun  3 18:13 VERSION
-rw-r--r-- 1     907 Jun  3 18:13 json
-rw-r--r-- 1 1035776 Jun  3 18:13 layer.tar
  1. Go into 983179bdb58ea980ec1fe7c45f63571d49b140bdd629f234be9c00a6edd8a4a7, untar layer.tar, and display:
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cd 983179bdb58ea980ec1fe7c45f63571d49b140bdd629f234be9c00a6edd8a4a7
tar xaf layer.tar
ls -AgGR
.:
total 1028
-rw-r--r-- 1       3 Jun  3 18:13 VERSION
drwxr-xr-x 2    4096 Jun  3 18:11 bin
-rw-r--r-- 1     907 Jun  3 18:13 json
-rw-r--r-- 1 1035776 Jun  3 18:13 layer.tar
drwxr-xr-x 2    4096 Jun  3 18:09 root

./bin:
total 2016
-rwxr-xr-x 2 1031328 Jun  3 18:11 cat
-rwxr-xr-x 2 1031328 Jun  3 18:11 sha1sum

./root:
total 4
-rw------- 1 44 Jun  3 18:12 .ash_history
  1. root/.ash_history looks intersting:
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cat root/.ash_history
not so easy bru - the infections is intense
  1. ... but is not. So let's see what are the binaries:
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cat bin/sha1sum
[...]
THIS IS WHAT YOU ARE LOOKING FOR:    0n3_n00b_ru1n5_0n3_hundr3d_pr05
  1. The last line of the binary shows us what we are looking for 0n3_n00b_ru1n5_0n3_hundr3d_pr05 (1337 : one noob ruins one hundred pros)
  2. Try to sha256 it:
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echo -n "0n3_n00b_ru1n5_0n3_hundr3d_pr05" | sha256sum
0743a3265649702df53b083056b2f426d20e449cd68210384ff0ff159f3867fa

PS : You could have seen that the repository has the structure of a docker image and try to load and build it.

Flag#

Since Backdoor is an always-online CTF platform, and not a one time contest, we kindly request you to not publish flags for the challenges in your writeups. Writeups are an excellent way to share knowledge and help others learn. In Backdoor, challenges are shifted from a contest to the Practice section, where people can continue to attempt them after the contest is over. It would be very unfair to participants if the flags for the problems were easily available in writeups online. Hence, we kindly request to not publish flags of the problems that you solve. Here is an example of an excellent writeup which refrains from giving the complete solution.

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