# SECCON CTF Quals - 2019
## Misc / 279 - Sandstorm 
> I've received a letter... Uh, Mr. Smith?> ![](./imgs/sandstorm.png)
### Solution
By [@afcidk](https://github.com/afcidk)
From the provided image, we can guess that this challenge is related to Adam7, which is an interlacing scheme for PNG images. Adam7 has seven passes, so I decide to generate those seven subimages first, and see if there is any clues.
I wrote a simple script to transform the original [sandstorm.png](./imgs/sandstorm.png) to seven images using Adam7 algorithm.
Level 1:![](./imgs/level1.png)
Level 2:![](./imgs/level2.png)
Level 3:![](./imgs/level3.png)
Level 4:![](./imgs/level4.png)
Level 5:![](./imgs/level5.png)
Level 6:![](./imgs/level6.png)
Level 7:![](./imgs/level7.png)
The flag is encoded to QR code in Level-1 subimage, `SECCON{p0nlMpzlCQ5AHol6}`.
### Reference
* [Adam7 algorithm](https://en.wikipedia.org/wiki/Adam7_algorithm)