From 92aeb46d1c8ffe417f16f01132d560c873c4dbc2 Mon Sep 17 00:00:00 2001 From: David Fifield Date: Fri, 24 Mar 2017 19:45:49 -0700 Subject: [PATCH] Hexable writeup. Adapted from https://www.bamsoftware.com/computers/easyctf-2017/#hexable --- SUMMARY.md | 1 + reverse-engineering.md | 2 +- reverse-engineering/hexable-25-points.md | 22 ++++++++++++++++++++++ 3 files changed, 24 insertions(+), 1 deletion(-) create mode 100644 reverse-engineering/hexable-25-points.md diff --git a/SUMMARY.md b/SUMMARY.md index d3888f6..ef68ce4 100644 --- a/SUMMARY.md +++ b/SUMMARY.md @@ -25,6 +25,7 @@ * [Fzz Buzz 2 \[200 points\]](/programming/fzz-buzz-2-200-points.md) * [Match Me \[300 points\]](/programming/match-me-300-points.md) * [Reverse Engineering](reverse-engineering.md) + * [Hexable \[25 points\]](/reverse-engineering/hexable-25-points.md) * [Useless Python \[50 points\]](/reverse-engineering/useless-python-50-points.md) * [Phunky Python II \[115 points\]](/reverse-engineering/phunky-python-ii-115-points.md) * [Hex QR \[200 points\]](/reverse-engineering/hexqr-200-points.md) diff --git a/reverse-engineering.md b/reverse-engineering.md index a99651f..d0794f9 100644 --- a/reverse-engineering.md +++ b/reverse-engineering.md @@ -2,7 +2,7 @@ This category challenges your deductive ability to use a program's behavior and output to figure out its input, thus reversing the original behavior of the program. The reverse engineering challenges for this contest are: -* Hexable \[25 points\] +* [Hexable \[25 points\]](/reverse-engineering/hexable-25-points.md) * Phunky Python I \[30 points\] * [Useless Python \[50 points\]](//reverse-engineering/useless-python-50-points.md) * [Phunky Python II \[115 points\]](//reverse-engineering/phunky-python-ii-115-points.md) diff --git a/reverse-engineering/hexable-25-points.md b/reverse-engineering/hexable-25-points.md new file mode 100644 index 0000000..47e9a0c --- /dev/null +++ b/reverse-engineering/hexable-25-points.md @@ -0,0 +1,22 @@ +# Hexable - 25 points + +I tried to hide a flag sneakily, can you find it? [Download](https://github.com/EasyCTF/easyctf-2017-problems/blob/master/hexable-autogen/hexable) + +### Solution + +The challenge file was a small executable of 235 bytes: + +``` +$ file hexable +85b33e8a48a9e129d23c20483b4b12cd1d199708_hexable: ELF 32-bit LSB executable, Intel 80386, version 1 (GNU/Linux), statically linked, stripped +``` + +[strings](https://en.wikipedia.org/wiki/Strings_%28Unix%29) was lucky and found a flag in plaintext. + +``` +$ strings -a hexable +Can you find the flag? +easyctf{PT4z0pqN1xQuXm} +``` + +### External Writeups