**Challenge Description**:
Similar to Stack Strings 1 but with a more complex verification loop.

**Analysis**:
The binary checks input length (41 chars) and then enters a loop that:
1. Computes a pseudo-random index `k` based on TEA and a permutation array.
2. Loads `input[k]`.
3. Updates a rolling accumulator `acc` using `input[k]` and a key byte.
4. Compares `acc` against a target value stored in another array.

**Solution**:
1. Dumped the permutation array (`0xa2`) and target array (`0xcb`) from memory using GDB.
2. Wrote a solver `solve_stack2.py` that simulates the loop in reverse.
3. Since the initial accumulator state was unknown (derived from uninitialized memory or stack garbage), we brute-forced the single starting byte (256 possibilities) until the output contained `ENO`.

**Solver**: [solve_stack2.py](file:///home/mritunjya/ctf/2026/nullcon/rev/stack_strings_2/solve_stack2.py)

**Flag**: `ENO{W0W_D1D_1_JU5T_UNLUCK_4_N3W_SK1LL???}`