Tags: miscellaneous forensics misc
Rating:
# Access Denied 1.2 2018 – BitMapElf
* **Category:** forensics
* **Points:** 300
## Challenge
> A bitmap defines a display space and the color for each pixel or "bit" in the display space.
>
> Can you get the flag out using bit mapping ?
>
> Challenge running at : [https://bitmapelf.herokuapp.com](https://bitmapelf.herokuapp.com)
## Solution
The referred website contains [a page with an HTML table](https://bitmapelf.herokuapp.com). Each table row contains cells with `bgcolor` attributes set to hexadecimal numbers.
```html
<td bgcolor="#7f454c" height="25" width="25"></td>
<td bgcolor="#460201" height="25" width="25"></td>
<td bgcolor="#010000" height="25" width="25"></td>
<td bgcolor="#000000" height="25" width="25"></td>
<td bgcolor="#000000" height="25" width="25"></td>
<td bgcolor="#000200" height="25" width="25"></td>
<td bgcolor="#3e0001" height="25" width="25"></td>
<td bgcolor="#000000" height="25" width="25"></td>
<td bgcolor="#e00840" height="25" width="25"></td>
<td bgcolor="#000000" height="25" width="25"></td>
<td bgcolor="#000040" height="25" width="25"></td>
<td bgcolor="#000000" height="25" width="25"></td>
<td bgcolor="#000000" height="25" width="25"></td>
And so on...
```
These numbers can be interpreted like background colors or, considering the name of the challenge, like the binary representation of an ELF file.
Extracting all the hexadecimal numbers will give the following data:
```
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```
First bytes are the ELF file signature, i.e. `7f454c46`.
Using an hexadecimal editor, the [real ELF file](https://github.com/m3ssap0/CTF-Writeups/raw/master/Access%20Denied%201.2%202018/BitMapElf/foren300) can be crafted.
Running the ELF file will not show any output.
Using the `strings` command (or looking into the binary file with the hexadecimal editor) will reveal the flag:
```
accessdenied{c0l0r5_ar3_aw3s0m3}
```
