Rating:
# SarCTF 2020 -- Layouts (Misc) -- 866 pts
We're given a file named as "RWtm7A5f", its a zip compressed file:
```
root@kali:~/ctf/sarctf/layouts# file RWtm7A5f
RWtm7A5f: Zip archive data, at least v2.0 to extract
```
Extracting the zip file, we get another compressed file (Matroska challenge-like), so we have built a script to deal with it:
```
root@kali:~/ctf/sarctf/layouts/solve-first-step# ls
RWtm7A5f solve.sh
root@kali:~/ctf/sarctf/layouts/solve-first-step# ./solve.sh
....................
Archive: VRdCccaT.zip
inflating: RDkJMKDa
Archive: RDkJMKDa.zip
inflating: 85iVroNS
Archive: 85iVroNS.zip
inflating: kSPrXQjZ
Archive: kSPrXQjZ.zip
extracting: flag
Archive: flag.zip
End-of-central-directory signature not found. Either this file is not
a zipfile, or it constitutes one disk of a multi-part archive. In the
latter case the central directory and zipfile comment will be found on
the last disk(s) of this archive.
unzip: cannot find zipfile directory in one of flag or
flag.zip, and cannot find flag.ZIP, period.
[+] flag file
root@kali:~/ctf/sarctf/layouts/solve-first-step# ls flags/
1 105 111 118 124 130 137 143 15 156 162 169 175 181 188 194 20 206 212 219 225 231 238 244 250 27 33 4 46 52 59 65 71 78 84 90 97
10 106 112 119 125 131 138 144 150 157 163 17 176 182 189 195 200 207 213 22 226 232 239 245 251 28 34 40 47 53 6 66 72 79 85 91 98
100 107 113 12 126 132 139 145 151 158 164 170 177 183 19 196 201 208 214 220 227 233 24 246 252 29 35 41 48 54 60 67 73 8 86 92 99
101 108 114 120 127 133 14 146 152 159 165 171 178 184 190 197 202 209 215 221 228 234 240 247 253 3 36 42 49 55 61 68 74 80 87 93
102 109 115 121 128 134 140 147 153 16 166 172 179 185 191 198 203 21 216 222 229 235 241 248 254 30 37 43 5 56 62 69 75 81 88 94
103 11 116 122 129 135 141 148 154 160 167 173 18 186 192 199 204 210 217 223 23 236 242 249 255 31 38 44 50 57 63 7 76 82 89 95
104 110 117 123 13 136 142 149 155 161 168 174 180 187 193 2 205 211 218 224 230 237 243 25 26 32 39 45 51 58 64 70 77 83 9 96
```
As you could see, there are a bunch of folders in there, each folder has one empty file:
```
root@kali:~/ctf/sarctf/layouts/solve-first-step# find flags/ -type f
flags/125/21
flags/53/17
flags/95/15
flags/83/1
flags/52/7
flags/52/14
flags/89/2
flags/101/9
flags/84/4
flags/78/3
flags/51/10
flags/102/11
flags/112/18
flags/120/13
flags/110/16
flags/103/8
flags/49/19
flags/49/20
flags/122/6
flags/123/5
flags/117/12
```
125, 53, 95, 101, 89, hm... all of those "numbers" are ASCII Readable chars, maybe those files "sequentially" created within those "random" folders should give us a guide of which characters should be read first, let's try it.
So I created a script "stego.py" which will decode those ASCII codes following the "guide" by reading the file "out-sorted.txt":
```
root@kali:~/ctf/sarctf/layouts# cat out-sorted.txt
83,1
89,2
78,3
84,4
123,5
122,6
52,7
103,8
101,9
51,10
102,11
117,12
120,13
52,14
95,15
110,16
53,17
112,18
49,19
49,20
125,21
root@kali:~/ctf/sarctf/layouts# python stego.py
SYNT{z4ge3fux4_n5p11}
```
It looks like it got encoded using Caesar Cipher, let's decode it using https://www.dcode.fr/caesar-cipher:
(shift) +13 (text) FLAG{m4tr3shk4_a5c11}
#### FLAG{m4tr3shk4_a5c11}
