Reverse › Module 6 › Lesson 4
Lab — Dynamic
End-to-end dynamic RE pass on $RE_LAB crackme — GDB session, breakpoints, trace excerpt, execution notes tied to static work.
Visual · t23_dynamic_lab
Lab: dynamic RE on YOUR $RE_LAB crackme. Original Cyberlium.
Opening
Close one dynamic loop — static address to breakpoint to register proof — on a binary you are allowed to break.
On YOUR $RE_LAB crackme or CTF binary per brief: (1) verify hash and legal target; (2) load in GDB with static addresses from Module 5; (3) set ≥2 breakpoints at decision points; (4) run bounded trace (strace or ltrace) capturing ≥5 rows; (5) document one successful path observation: registers/flags at compare, branch taken, output string; (6) cross-link static Ghidra/objdump notes; (7) chmod 600 lab pack. No commercial software, no piracy patches, no anti-debug bypass beyond literacy documentation. Stop if target undocumented.
1. Lab pipeline
Static address → breakpoint → observe → trace excerpt → summary — same order builds RE habit.
Header: binary hash, $RE_LAB VM name, UTC session time.
Command guide
Try these commands — Lab pipeline
═══ TOOLS & WEBSITES ═══ Browse / read these (authorized learning only — stay in YOUR lab / program scope)
Dynamic RE lab — https://pwn.college/ (trace YOUR compiled toys) GDB cheat sheet — https://sourceware.org/gdb/current/onlinedocs/gdb.html/Command-Index.html objdump + gdb — https://man7.org/linux/man-pages/man1/objdump.1.html (static then dynamic)
═══ INSTALL ═══
Linux (Debian/Ubuntu):
Command — copy this
sudo apt install gdb sudo apt install binutils
macOS:
Command — copy this
brew install gdb
Built-in (Xcode CLI) or brew install binutils
Windows: Use WSL gdb Use WSL binutils
═══ LINUX / macOS ═══
Command — copy this
export LAB_RE=${LAB_RE:-$HOME/cyberlium-lab/t23-re}
objdump -d "$LAB_RE/bin/branch" | grep -A15 '<pick>:' | head -17
gdb -q -batch -ex 'break pick' -ex 'run' -ex 'disassemble' -ex quit "$LAB_RE/bin/branch" 2>/dev/null | head -25
echo 'dynamic lab: YOUR toys only — never attach gdb to commercial binaries'═══ WINDOWS ═══
Command — copy this
Write-Output 'Use WSL or lab VM for gdb on YOUR gcc toys — never commercial targets'
Primary tools to practice this lesson: gdb, objdump. Reference sites: Dynamic RE lab (https://pwn.college/); GDB cheat sheet (https://sourceware.org/gdb/current/onlinedocs/gdb.html/Command-Index.html); objdump + gdb (https://man7.org/linux/man-pages/man1/objdump.1.html). Run every command in the box — install first, then the usage lines — only on YOUR lab / program scope.
2. Evidence rows
Each row: breakpoint hit, register snapshot, branch outcome, correlated static label.
Distinguish observed vs inferred — honesty for reporting module.
3. Stop conditions
Stop if binary not crackme/CTF/YOUR toy, or brief forbids file class.
Refused: patch license on commercial binary in this lab — observe only.
4. What you ship: dynamic lab pack
GDB session log + ≥2 breakpoints + trace excerpt + execution summary — chmod 600.
5. What you record before the next lesson
Dynamic lab pack path.
6. Wrong vs right: commercial piracy vs crackmes/CTF toys
Worked failure — same MSF word, opposite target. Right never needs a café Wi-Fi or classmate laptop.
Wrong
Dynamic lab on pirated commercial executable 'for practice.'
Right
Dynamic lab pack on $RE_LAB crackme. Next: quiz.
Mission: dynamic lab
1) Verify hash and scope. 2) GDB with two breakpoints and register proof. 3) Trace excerpt ≥5 rows. 4) Cross-link static notes; chmod 600.
Stuck? Ask Cyberlium AI Mentor
Ask Mentor: “Minimum register proof for compare branch?”
Knowledge Check
APPLY: Dynamic lab scope:
Multiple choice
Knowledge Check
APPLY: True or False: Patch commercial license in dynamic lab earns credit.
True or False
Knowledge Check
APPLY: Dynamic lab pack includes:
Multiple choice