desc

binary-exploitation/var-control-w/DESCRIPTION.md

@@ -1 +1,12 @@
-Overflow a buffer on the stack to set trickier conditions to obtain the flag!
+So far, your buffer overflows have simply set variables to non-zero values.
+Of course, memory errors often enable significantly more advanced controls over a program's state.
+In this challenge, you must overflow the buffer precisely to set a win condition variable to a specific value.
+Some things to keep in mind:
+
+- You will need to write binary data.
+  This can't be printed on the keyboard; we recommend that you use something like Python to produce these bytes.
+- Keep endianness in mind!
+- Depending on how you generate the input data, you might accidentally terminate it with a newline!
+  For example, bash's `echo` will newline-terminate by default (this behavior can be disabled using the `-n` flag).
+  These newlines can cause problems --- if you are relying on precise control of program variables (which you are, in this module), an errant newline can unexpectedly corrupt program state and break your exploit.
+  If you have doubts about whether your input has an errant newline, save it to a file and look at it using a hex dumper such as `hd`.