Solution for EZ

Author: mzfr

Securinets_Prequals_2K19/misc/EZ/README.md

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+# EZ
+
+__PROBLEM__
+
+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 Link](pic.zip)
+
+Author:BlueWhale
+
+
+__SOLUTION__
+
+Again I started with strings followed by exiftool and then binwalk and none of those gave anything interesting. And then I noticed that the image is of `.png` format that means we can use `zsteg` on that image.
+
+```bash
+➜ zsteg pic.png
+b1,rgb,lsb,xy       .. text: "--START--\n\"The fact is that upon his entrance I had instantly recognized the extreme\npersonal danger in which I lay. The only conceivable escape for him lay in silencing\nmy tongue. In an instant I had slipped the revolver from the drawer into my\npocket and"
+b2,b,msb,xy         .. text: "_uW}W}W}"
+b3,b,lsb,xy         .. file: very old 16-bit-int big-endian archive
+b4,r,lsb,xy         .. text: "\nvvwgffwfwvwgg"
+b4,g,lsb,xy         .. text: "gwvwvffwvgvfggfvwgvfvgfgvgffvwfvwgfvfgvvwwvfwgfwfgvgvgffwgffffffwgfffgfgvwvfwgvfwwfwvwfgvwvfwgvffgvfvwffwgvwvwvfggffvgfgwgfffgvfwgvfvgffwgfwwgfgwgfffgvfwwvfvgfffgvgwgffvwvgvwvfvgfgwgvfvwfgvwfffgvgvgffwwvfwgfvfgfgfgffwgvgvwfgvvffwwfvwwvgvwvgfffgfgfgfgfgvwvf"
+b4,b,lsb,xy         .. text: "wfgggfgfgffwffwfvfffwfggwfgwvfgfvfgfvggfwfvfvfggvfgvwgwgwfwgvfffvfgfvfgvvgggwggvvfgfwfwwwfwwvfgfvggvwfggvggfwfggfgggvgwwwfgvvfggwfwgvfgwwfggvfggvfgwvfggvfvfgfggvfwvwgffvfwvvfgwwfgfwfffwgwgvgggvfwwvfgvvfffwfgwvfgvvgwwwfgvvfgvwfwwvfgfwfwgwffvvfgvvfgvvfgvvggg"
+b4,rgb,lsb,xy       .. text: "ogWef&vfFmw"
+b4,rgb,msb,xy       .. text: "`vnovng>"
+b4,bgr,lsb,xy       .. text: "ogVev&ffG}g"
+```
+
+This show that there's some strings hidden there, let's extract that
+
+```
+--START--
+"The fact is that upon his entrance I had instantly recognized the extreme
+personal danger in which I lay. The only conceivable escape for him lay in silencing
+my tongue. In an instant I had slipped the revolver from the drawer into my
+pocket and was covering him through the cloth. At his remark I drew the weapon
+out and laid it cocked upon the table. He still smiled and blinked, but there was
+something 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 take
+a 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 some
+dates.
+"You crossed my path on the fourth of January,' said he. 'On the twenty-third
+you incommoded me; by the middle of February I was seriously inconvenienced
+by you; at the end of March I was absolutely hampered in my plans; and now, at
+the close of April, I find myself placed in such a position through your continual
+persecution that I am in positive danger of losing my liberty. The situation is
+becoming an impossible one.'
+"'Have you any suggestion to make?' I asked.
+"'You must drop it, Mr. Holmes,' said he, swaying his face about. 'You really
+must, you know.'"
+--END--
+```
+
+This is what we get from the extracted data and now all we have to do is to find the `<DELETED_WORD>`. Simply google any part of the paragraph and it will give us the [original](https://www.pagebypagebooks.com/Arthur_Conan_Doyle/Memoirs_of_Sherlock_Holmes/Adventure_XI_The_Final_Problem_p4.html)
+
+After comparing with original we found out that the missing word is `memorandum-book`, but submitting the sha1 of this string didn't worked so we tried with `memorandumbook`
+
+```bash
+➜ echo "memorandumbook" | sha1sum
+3e06c0914406bcd91c6326d32a75be36dd44a2d4
+```
+FLAG - Securinets{3e06c0914406bcd91c6326d32a75be36dd44a2d4}