# Securinets Prequals CTF 2019 – EZ
* **Category:** Misc* **Points:** 331
## Challenge
> Welcome to Securinets, this one is an easy one.>> Please make sure you hash the WORD with sha1 (lowercase hash letter)>> The final flag is : Securinets{the_hash_of_the_word}>> [pic.png](https://github.com/m3ssap0/CTF-Writeups/raw/master/Securinets%20Prequals%20CTF%202019/EZ/pic.png)>> Author:BlueWhale
## Solution
The challenge gives the following PNG file to analyze.
![pic.png](https://github.com/m3ssap0/CTF-Writeups/raw/master/Securinets%20Prequals%20CTF%202019/EZ/pic.png)
One of the basic techniques of steganography is to hide information into MSB or LSB of an image.
[SHIT - Stego Helper Identification Tool](https://github.com/qll/shit) is a tool which allows to retrieve that information.
Launching the tool with the following command
```python retrieve.py bit 7 pic.png ```
will retrieve the following text.
```--START--"The fact is that upon his entrance I had instantly recognized the extremepersonal danger in which I lay. The only conceivable escape for him lay in silencingmy tongue. In an instant I had slipped the revolver from the drawer into mypocket and was covering him through the cloth. At his remark I drew the weaponout and laid it cocked upon the table. He still smiled and blinked, but there wassomething about his eyes which made me feel very glad that I had it there,"You evidently don't know me,' said he."'On the contrary,' I answered, 'I think it is fairly evident that I do. Pray takea chair. I can spare you five minutes if you have anything to say.'"'All that I have to say has already crossed your mind,' said he."'Then possibly my answer has crossed yours,' I replied."'You stand fast?'"'Absolutely.'"He clapped his hand into his pocket, and I raised the pistol from the table.But he merely drew out a <DETELED_WORD> in which he had scribbled somedates."You crossed my path on the fourth of January,' said he. 'On the twenty-thirdyou incommoded me; by the middle of February I was seriously inconveniencedby you; at the end of March I was absolutely hampered in my plans; and now, atthe close of April, I find myself placed in such a position through your continualpersecution that I am in positive danger of losing my liberty. The situation isbecoming an impossible one.'"'Have you any suggestion to make?' I asked."'You must drop it, Mr. Holmes,' said he, swaying his face about. 'You reallymust, you know.'"--END--;```
In that text there is a `<DETELED_WORD>`. Googling the text, you can discover that the deleted word is: `memorandum-book`.
The SHA-1 hash of that word is: `b47f0d2a8866a75696f94a515d0cdf54c7ea3174`.
Hence the flag is the following.
```Securinets{b47f0d2a8866a75696f94a515d0cdf54c7ea3174}```