Reverse › Module 5 › Lesson 1
objdump readelf
CLI static triage with objdump and readelf — disassemble YOUR toy binaries on $RE_LAB, never unauthorized commercial dumps.
Visual · re_objdump_readelf
objdump/readelf literacy. $RE_LAB only. Original Cyberlium.
Opening
objdump -d and readelf -h are the first terminal stops before GUI disassemblers.
objdump disassembles.text (-d), shows headers (-x), and dumps dynamic relocations. readelf exposes ELF structure (-h, -S, -s, -d). Together they triage Linux crackmes and YOUR toy binaries on $RE_LAB without launching a GUI — fast checks before Ghidra import. Cyberlium teaches CLI static literacy as foundation. You will NOT pipe objdump output from commercial warez into public paste sites with crack steps. Next: Ghidra Literacy.
1. readelf triage commands
readelf -h: ELF header. -S: sections. -s: symbol table. -d: dynamic segment. Run on YOUR toy in $RE_LAB; save output snippet to chmod 600 notes.
Compare entry from -h with objdump -d start address — consistency check before deep RE.
Command guide
Try these commands — readelf triage commands
═══ TOOLS & WEBSITES ═══ Browse / read these (authorized learning only — stay in YOUR lab / program scope)
objdump manual — https://sourceware.org/binutils/docs/binutils/objdump.html readelf manual — https://man7.org/linux/man-pages/man1/readelf.1.html GNU binutils — https://sourceware.org/binutils/docs/binutils/
═══ INSTALL ═══
Linux (Debian/Ubuntu):
Command — copy this
sudo apt install binutils
macOS: Built-in (Xcode CLI) or brew install binutils
Command — copy this
brew install binutils
Windows: Use WSL binutils
═══ LINUX / macOS ═══
Optional command
sudo apt install binutils # objdump readelf nm
Command — copy this
export LAB_RE=${LAB_RE:-$HOME/cyberlium-lab/t23-re}
objdump -d "$LAB_RE/bin/check" | grep -A12 '<main>:' | head -14
readelf -d "$LAB_RE/bin/check" 2>/dev/null | head -10
objdump -x "$LAB_RE/bin/check" | head -20Primary tools to practice this lesson: objdump, readelf. Reference sites: objdump manual (https://sourceware.org/binutils/docs/binutils/objdump.html); readelf manual (https://man7.org/linux/man-pages/man1/readelf.1.html); GNU binutils (https://sourceware.org/binutils/docs/binutils/). Run every command in the box — install first, then the usage lines — only on YOUR lab / program scope.
2. objdump disassembly
objdump -d -M intel binary shows Intel syntax disassembly; -D disassembles all sections. -T lists dynamic symbols; -R relocations.
Pipe through less; grep for main, check, strcmp to find gate functions in toy binary.
3. CLI literacy boundaries
Forbidden: publishing objdump-guided cracks for commercial software, analyzing unauthorized binaries from employer without policy, or automating mass piracy scans.
Ship: command cheat sheet — five readelf/objdump flags with one-line purpose each. Next: Ghidra Literacy.
4. What you ship: objdump/readelf cheat sheet for $RE_LAB
Five CLI flags with purposes + one grep target from YOUR toy. $RE_LAB named. NEVER commercial crack guides. chmod 600.
5. What you record before the next lesson
Date. CLI cheat sheet. $RE_LAB named. File t23-m05-l01-objdump-readelf.txt chmod 600.
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
Post objdump crack steps for paid app. Run objdump on host warez folder.
Right
Write objdump/readelf cheat sheet from $RE_LAB toy triage. Next: Ghidra Literacy.
Mission: build YOUR CLI cheat sheet
1) List five readelf/objdump flags. 2) Grep one gate symbol in YOUR toy output. 3) chmod 600.
Stuck? Ask Cyberlium AI Mentor
CLI triage is fast — GUI comes after headers make sense.
Knowledge Check
APPLY: objdump/readelf literacy means:
Multiple choice
Knowledge Check
APPLY: True or False: readelf -h shows the ELF header.
True or False
Knowledge Check
APPLY: objdump -d primarily disassembles:
Multiple choice