This repository, at the time of writing, will just host a listing of tools and commands that may help with CTF challenges. I hope to keep it as a "live document," and ideally it will not die out like the old "tools" page I had made ([https://github.com/USCGA/tools](https://github.com/USCGA/tools)).
Hopefully, at some point I will develop software that will run through a lot of the low-hanging fruit and simple command-line tools, generate a report and have all the output in one place.
A [Java][Java] [`.JAR`][JAR] tool, that can extract data from an image. A good tool to use on guessing challenges, when you don't have any other leads. We found this tool after the [Misc50](http://0xahmed.ninja/nullcon-hackim18-ctf-writeups/) challenge from [HackIM 2018](https://ctftime.org/event/566)
* [`Stegsolve.jar`][Stegsolve.jar]
A [Java][Java] [`.JAR`][JAR] tool, that will open an image and let you as the user arrow through different renditions of the image (viewing color channels, inverted colors, and more). The tool is surprisingly useful.
Tabs and spaces could be representing 1's and 0's and treating them as a binary message... or, they could be whitespace done with [`snow`][snow] or an esoteric programming language interpreter: [http://ws2js.luilak.net/interpreter.html](http://ws2js.luilak.net/interpreter.html)
Some classic challenges use an audio file to hide a flag or other sensitive stuff. SONIC visualizer easily shows you [spectrogram](https://en.wikipedia.org/wiki/Spectrogram). __If it sounds like there is random bleeps and bloops in the sound, try this tactic!__
Audio frequencies common to a phone button, DTMF: [https://en.wikipedia.org/wiki/Dual-tone_multi-frequency_signaling](https://en.wikipedia.org/wiki/Dual-tone_multi-frequency_signaling).
* [`hipshot`][hipshot]
A [Python] module to compress a video into a single standalone image, simulating a long-exposure photograph. Was used to steal a [QR code] visible in a video, displayed through "Star Wars" style text motion.
* [QR code]
A small square "barcode" image that holds data.
* [`zbarimg`][zbarimg]
A command-line tool to quickly scan multiple forms of barcodes, [QR codes] included. Installed like so on a typical [Ubuntu] image:
ANY text could be XOR'd. Techniques for this are Trey's code, and XORing the data against the known flag format. Typically it is given in just hex, but once it is decoded into raw binary data, it gives it keeps it's hex form (as in `\xde\xad\xbe\xef` etc..) Note that you can do easy XOR locally with Python like so (you need `pwntools` installed):
The most classic shift cipher. Tons of online tools like this: [https://www.dcode.fr/caesar-cipher](https://www.dcode.fr/caesar-cipher) or use `caesar` as a command-line tool (`sudo apt install bsdgames`) and you can supply a key for it. Here's a one liner to try all letter positions:
```
cipher='jeoi{geiwev_gmtliv_ws_svmkmrep}' ; for i in {0..25}; do echo $cipher | caesar $i; done
```
__Be aware!__ Some challenges include punctuation in their shift! If this is the case, try to a shift within all 255 ASCII characters, not just 26 alphabetical letters!
*`caesar`
A command-line caesar cipher tool (noted above) found in the `bsdgames` package.
The telltale sign for this kind of challenge is an enormously large `e` value. Typically `e` is either 65537 (0x10001) or `3` (like for a Chinese Remainder Theorem challenge)
* RSA: Chinese Remainder Attack
These challenges can be spotted when given mutiple `c` cipher texts and multiple `n` moduli. `e` must be the same number of given `c` and `n` pairs.
The go-to tool for examining [`.pcap`][PCAP] files.
* [Network Miner]
Seriously cool tool that will try and scrape out images, files, credentials and other goods from [PCAP] and [PCAPNG] files.
* [PCAPNG]
Not all tools like the [PCAPNG] file format... so you can convert them with an online tool [http://pcapng.com/](http://pcapng.com/) or from the command-line with the `editcap` command that comes with installing [Wireshark]:
```
editcap old_file.pcapng new_file.pcap
```
* [`tcpflow`][tcpflow]
A command-line tool for reorganizing packets in a PCAP file and getting files out of them. __Typically it gives no output, but it creates the files in your current directory!__
```
tcpflow -r my_file.pcap
ls -1t | head -5 # see the last 5 recently modified files
A common vulnerability in [PHP] that fakes hash "collisions..." where the `==` operator falls short in [PHP] type comparison, thinking everything that follows `0e` is considered scientific notation (and therefore 0). More valuable info can be found here: [https://github.com/spaze/hashes](https://github.com/spaze/hashes), but below are the most common breaks.
A command-line tool to decode [`bcompiler`][bcompiler] compiled [PHP] code.
* [`php://filter` for Local File Inclusion](https://www.idontplaydarts.com/2011/02/using-php-filter-for-local-file-inclusion/)
A bug in [PHP] where if GET HTTP variables in the URL are controlling the navigation of the web page, perhaps the source code is `include`-ing other files to be served to the user. This can be manipulated by using [PHP filters](http://php.net/manual/en/filters.php) to potentially retrieve source code. Example like so:
A comand-line tool to __recover a password from a PDF file.__ Supports dictionary wordlists and bruteforce.
*`pdfimages`
A command-line tool, the first thing to reach for when given a PDF file. It extracts the images stored in a PDF file, but it needs the name of an output directory (that it will create for) to place the found images.
The starting values that identify a file format. These are often crucial for programs to properly read a certain file type, so they must be correct. If some files are acting strangely, try verifying their [magic number] with a [trusted list of file signatures](https://en.wikipedia.org/wiki/List_of_file_signatures).
* [`hexed.it`][hexed.it]
An online tool that allows you to modify the hexadecimal and binary values of an uploaded file. This is a good tool for correcting files with a corrupt [magic number]
* [`dumpzilla`][dumpzilla]
A [Python] script to examine a `.mozilla` configuration file, to examine downloads, bookmarks, history or bookmarks and registered passwords. Usage may be as such:
A command-line tool to carve files out of another file. Usage is `foremost [filename]` and it will create an `output` directory.
```
sudo apt install foremost
```
*`binwalk`
A command-line tool to carve files out of another file. Usage to extract is `binwalk -e [filename]` and it will create a `_[filename]_extracted` directory.
This file tries to hide webpages from web crawlers, like Google or Bing or Yahoo. A lot of sites try and use this mask sensitive files or folders, so it should always be some where you check during a CTF. [http://www.robotstxt.org/](http://www.robotstxt.org/)
This directory is often found by directory scanning bruteforce tools, so I recommend just checking the directory on your own, as part of your own "low-hanging fruits" check.
A classic CTF challenge is to leave a `git` repository live and available on a website. You can see this with `nmap -A` (or whatever specific script catches it) and just by trying to view that specific folder, `/.git/`. A good command-line tool for this is [`GitDumper.sh`][https://github.com/internetwache/GitTools], or just simply using [`wget`][wget].
* [`GitDumper.sh`][GitDumper.sh]
A command-line tool that will automatically scrape and download a [git] repository hosted online with a given URL.
[XSS Filter Evasion Cheat Sheet](https://www.owasp.org/index.php/XSS_Filter_Evasion_Cheat_Sheet). [Cross-site scripting], vulnerability where the user can control rendered [HTML] and ideally inject [JavaScript] code that could drive a browser to any other website or make any malicious network calls. Example test payload is as follows:
A sliding puzzle that consists of a 4x4 grid with numbered square tiles, with one missing, set in a random order. It was involved in SharifCTF to determine if a group of these puzzles was solvable: [https://theromanxpl0it.github.io/ctf_sharifctf18/fifteenpuzzle/](https://theromanxpl0it.github.io/ctf_sharifctf18/fifteenpuzzle/)
