rev/simple-asm (#16)

* t

* deployment fixes and some yaml + sol tweaks

---------

Co-authored-by: mud-ali <[email protected]>

no-asm-required/Dockerfile

@@ -0,0 +1,29 @@
+FROM --platform=linux/amd64 ubuntu@sha256:86ac87f73641c920fb42cc9612d4fb57b5626b56ea2a19b894d0673fd5b4f2e9 AS build
+
+RUN apt-get update -y && apt-get install -y gcc wget unzip && rm -rf /var/lib/apt/lists/*
+
+RUN wget -O ynetd.c https://raw.githubusercontent.com/johnsonjh/ynetd/master/ynetd.c \
+  && gcc -o ynetd ynetd.c \
+  && rm -f /tmp/ynetd.zip
+
+COPY main.c .
+
+RUN gcc -o chall main.c
+
+FROM --platform=linux/amd64 ubuntu@sha256:86ac87f73641c920fb42cc9612d4fb57b5626b56ea2a19b894d0673fd5b4f2e9
+
+RUN useradd -m -d /home/ctf -u 12345 ctf
+WORKDIR /home/ctf
+
+COPY --from=build chall chall
+COPY --from=build ynetd ynetd
+
+RUN chmod +x ./ynetd
+
+COPY flag.txt .
+
+RUN chown -R root:root /home/ctf
+
+USER ctf
+EXPOSE 9999
+CMD ./ynetd -p 9999 ./chall

no-asm-required/chall.yaml

@@ -0,0 +1,23 @@
+name: No Assembly Required
+categories:
+  - rev
+value: 50
+flag:
+  file: ./flag.txt
+description: >-
+  That's right! This challenge works right out of the box!
+  No need to assemble anything, all totally preassembled.
+hints:
+  - If it comes pre-assembled, all you can do is disassemble right?
+  - Have you heard of Ghidra?
+files:
+  - src: /home/ctf/chall
+    dest: chall
+    container: nc
+authors:
+  - Andrew
+visible: true
+deploy:
+  nc:
+    build: .
+    expose: 9999/tcp

no-asm-required/flag.txt

@@ -0,0 +1 @@
+ camp{FACT:CPUs_arE_pRe_A5SEmbLed_too..._0caec8a70f9a2}

no-asm-required/main.c

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+#include <stdio.h>
+#include <stdlib.h>
+
+static int NO_ONE_WILL_EVER_FIND_THIS_mwahahahahaha = 0x6FED;
+
+int main(int argv, char **argc) {
+
+    setvbuf(stdout, NULL, _IONBF, 0);
+    setvbuf(stdin, NULL, _IONBF, 0);
+    setvbuf(stderr, NULL, _IONBF, 0);
+
+    int lol = 0xf00d;
+
+    puts("Hey.");
+    sleep(1);
+    printf("Password? ");
+    int password = 0;
+    scanf("%d", &password);
+
+    int actual_password = lol | (NO_ONE_WILL_EVER_FIND_THIS_mwahahahahaha << 16);
+
+    if (actual_password == password) {
+        system("/bin/sh");
+    } else {
+        puts("Cool");
+        sleep(1);
+        puts("Yeah thats wrong!");
+    }
+
+    return 0;
+}
+
+// 
+// Hello people who solved this
+// How does it feel to have shell haha
+// 

no-asm-required/solve.md

@@ -0,0 +1,9 @@
+Decompile with Ghidra
+
+Read the source code
+
+figure out the password
+
+enter it into the netcat, gaining shell access. 
+
+Run `ls`, followed by `cat flag.txt` to get the flag.