Merge branch 'master' of github.com:bobacadodl/ctfx-problems

Author: omegablitz

binary/dat_boinary-250/deploy/Dockerfile

@@ -0,0 +1,8 @@
+FROM jaschac/debian-gcc:latest
+
+RUN apt-get update
+RUN apt-get install -y socat
+RUN rm -rf /var/lib/apt/lists/*
+RUN gcc -o dat_boinary -m32 -fno-stack-protector dat_boinary.c
+RUN rm dat_boinary.c
+RUN socat tcp-listen:1337,fork,reuseaddr exec:”./dat_boinary"

binary/dat_boinary-250/deploy/README.md

@@ -0,0 +1,4 @@
+# Deploy Instructions
+* cd into directory
+* `docker build -t ctfx/datboi .`
+* `docker run -p <host port>:1337 -d ctfx/datboi`

binary/dat_boinary-250/dat_boinary.c binary/dat_boinary-250/deploy/dat_boinary.c

@@ -14,12 +14,6 @@ def gcd(a, b):
         return a
     else:
         return gcd(b, a % b)
-def modinv(a, m):
-    g, x, y = xgcd(a, m)
-    if g != 1:
-        raise Exception('modular inverse does not exist! g=%i'%g)
-    else:
-        return x % m
 def solve(s):
     nrand = len(s)
     t = []

crypto/little_crypto_gambler-150/gamble_solution.py

@@ -0,0 +1,3 @@
+Mount the file system, find gesture.key, and follow this article:
+
+http://resources.infosecinstitute.com/android-forensics-cracking-the-pattern-lock-protection/

forensics/iTrash-100/writeup.txt

@@ -0,0 +1,4 @@
+Split cafebabe.jpg into equally sized digit images. XOR digit images with known
+digit images; the darkest image out of all of them is what the unknown digit image is.
+
+Extract the hex and run it as a java class file to get the flag.

misc/cafebabe-150/writeup.txt

@@ -0,0 +1 @@
+00011101010110111011111010110101010100101101011111100011000111000100010001001100110100001000011001110001111101101011110010010110110010111011000101111000011101000000111110011011000111111110101000001010011011000011001010000001110011101110101110111001001101011110111011001101100101111001111100001000010100001000000101111100111000110100001001111

misc/hows_the_cow-50/.python-version

@@ -0,0 +1,30 @@
+#this program decodes the full message, but due to precision errors,
+#the flag was changed to being the first 11 characters.
+
+s = "00011101010110111011111010110101010100101101011111100011000111000100010001001100110100001000011001110001111101101011110010010110110010111011000101111000011101000000111110011011000111111110101000001010011011000011001010000001110011101110101110111001001101011110111011001101100101111001111100001000010100001000000101111100111000110100001001111"
+val = int(s,2)
+ 
+print(val)
+ 
+# Base 26 Weighted by frequency
+prob = [0.08167, 0.01492, 0.02782, 0.04253, 0.12702, 0.02228, 0.02015, 0.06094, 0.06966, 0.00153, 0.00772, 0.04025, 0.02406, 0.06749, 0.07507, 0.01929, 0.00095, 0.05987, 0.06327, 0.09056, 0.02758, 0.00978, 0.0236, 0.0015, 0.01974, 0.00074]
+ 
+prefix = [0 for i in range(27)]
+prefix[0] = 0.0
+for i in range(1, 27):
+    prefix[i] = prefix[i - 1] + prob[i - 1]
+ 
+l = 80
+ans = ""
+delta = 2 ** len(s)
+for i in range(l):
+    tmp = [round(x*delta) for x in prefix]
+    it = 0
+    while it < 26 and tmp[it] < val:
+        it += 1
+    it -= 1
+    ans += chr(it + 97)
+    val -= tmp[it]
+    delta = tmp[it+1] - tmp[it]
+ 
+print(ans)

misc/hows_the_cow-50/flag.txt

@@ -1,3 +1 @@
-Arithmetic coding is great for sending secret messages.
-
-00011101010110111011111010110101010100101101011111100010000111111001000010100000011000010111101000001000011101010111000111000011011111011111101101100100001101110111111010101010011001100011101110010010101010000110100110001011100100110111010110100001101111111100100111000100100000001111000110011111100100010011001111010001000101100000100100011
+Arithmetic coding is great for sending secret messages.

misc/hows_the_cow-50/prob.py

@@ -0,0 +1,10 @@
+FROM openjdk:latest
+
+# Create app directory
+RUN mkdir -p /usr/src/app
+WORKDIR /usr/src/app
+
+COPY . /usr/src/app
+
+EXPOSE 8080
+CMD [ "java", "-jar", "harambehub.jar" ]

misc/hows_the_cow-50/statement.txt

@@ -0,0 +1,4 @@
+# Deploy Instructions
+* cd into directory
+* `docker build -t ctfx/harambehub .`
+* `docker run -p <host port>:8080 -d ctfx/harambehub`