--- name: binary-re-dynamic-analysis-9c4179228578 description: Use when you need to run a binary, trace execution, or observe runtime behavior. Runtime analysis via QEMU emulation, GDB debugging, and Frida hooking - syscall tracing (strace), breakpoints, memory inspection, function interception. Keywords - "run binary", "execute", "debug", "trace syscalls", "set breakpoint", "qemu", "gdb", "frida", "strace", "watch memory" --- # Dynamic Analysis (Phase 4) ## Purpose Observe actual runtime behavior. Verify hypotheses from static analysis. Capture data that's only visible during execution. ## Human-in-the-Loop Requirement **CRITICAL: All execution requires human approval.** Before running ANY binary: 1. Confirm sandbox configuration is acceptable 2. Verify network isolation if required 3. Document what execution will attempt 4. Get explicit approval ## Platform Support Matrix | Host Platform | Target Arch | Method | Complexity | |---------------|-------------|--------|------------| | Linux x86_64 | ARM32/64, MIPS | Native `qemu-user` | Low | | Linux x86_64 | x86-32 | Native or `linux32` | Low | | macOS (any) | ARM32/64 | Docker + binfmt | Medium | | macOS (any) | x86-32 | Docker `--platform linux/i386` | Medium | | Windows | Any | WSL2 → Linux method | Medium | ### macOS Docker Setup (One-Time) ```bash # Start Docker runtime (Colima, Docker Desktop, etc.) colima start # Register ARM emulation handlers (requires privileged mode) docker run --rm --privileged --platform linux/arm64 \ tonistiigi/binfmt --install arm ``` ### Docker Mount Best Practices **CRITICAL:** On Colima, `/tmp` mounts often fail silently. Always use home directory paths: ```bash # ✅ GOOD - use home directory docker run -v ~/code/samples:/work:ro ... # ❌ BAD - /tmp mounts can fail on Colima docker run -v /tmp/samples:/work:ro ... ``` --- ## Analysis Options | Method | Isolation | Granularity | Best For | |--------|-----------|-------------|----------| | QEMU -strace | High | Syscall level | Initial behavior mapping | | QEMU + GDB | High | Instruction level | Detailed debugging | | Docker | High | Process level | Cross-arch on macOS | | Frida | Medium | Function level | Hooking without recompilation | | On-device | Low | Full system | When emulation fails | ## Option A: QEMU User-Mode with Syscall Trace **Safest approach - runs in isolation with syscall logging.** ### Setup ```bash # Verify sysroot exists ls /usr/arm-linux-gnueabihf/lib/libc.so* # ARM 32-bit execution qemu-arm -L /usr/arm-linux-gnueabihf -strace -- ./binary # ARM 64-bit execution qemu-aarch64 -L /usr/aarch64-linux-gnu -strace -- ./binary ``` ### Sysroot Selection | Binary ABI | Sysroot Path | QEMU Flag | |------------|--------------|-----------| | ARM glibc hard-float | `/usr/arm-linux-gnueabihf` | `-L` | | ARM glibc soft-float | `/usr/arm-linux-gnueabi` | `-L` | | ARM64 glibc | `/usr/aarch64-linux-gnu` | `-L` | | ARM musl | Custom extraction needed | `-L` | ### Environment Control ```bash # Set environment variables qemu-arm -L /sysroot \ -E HOME=/tmp \ -E USER=nobody \ -E LD_DEBUG=bindings \ -- ./binary # Unset dangerous variables qemu-arm -L /sysroot \ -U LD_PRELOAD \ -- ./binary ``` ### Syscall Analysis Strace output patterns to watch: ```bash # Network activity openat.*socket connect(.*AF_INET sendto\|send\|write.*socket recvfrom\|recv\|read.*socket # File access openat.*O_RDONLY.*"/etc openat.*O_WRONLY stat\|lstat.*"/ # Process operations execve fork\|clone ``` ## Option B: QEMU + GDB for Deep Debugging **Attach debugger for instruction-level control.** ### Launch Binary Under GDB ```bash # Start QEMU with GDB server qemu-arm -g 1234 -L /usr/arm-linux-gnueabihf ./binary & # Connect with gdb-multiarch gdb-multiarch -q \ -ex "set architecture arm" \ -ex "target remote :1234" \ -ex "source ~/.gdbinit-gef.py" \ ./binary ``` ### GDB Commands for RE ```gdb # Breakpoints break *0x8400 # Address break main # Symbol break *0x8400 if $r0 == 5 # Conditional # Execution control continue # Run until break stepi # Single instruction nexti # Step over calls finish # Run until return # Inspection info registers # All registers x/20i $pc # Disassemble from PC x/10wx $sp # Stack contents x/s 0x12345 # String at address # Memory find 0x8000, 0x10000, "pattern" # Search memory dump memory /tmp/mem.bin 0x8000 0x9000 # Extract region ``` ### GEF Enhancements With GEF loaded, additional commands: ```gdb gef> vmmap # Memory layout gef> checksec # Security features gef> context # Full state display gef> hexdump qword $sp 10 # Better hex dump gef> pcustom # Structure definitions ``` ### Batch Debugging Script ```bash # Create GDB script cat > analyze.gdb << 'EOF' set architecture arm target remote :1234 break main continue info registers x/20i $pc continue quit EOF # Run batch gdb-multiarch -batch -x analyze.gdb ./binary ``` ## Option C: Frida for Function Hooking **Intercept function calls without modifying binary.** ⚠️ **Architecture Constraint:** Frida requires native-arch execution. It **cannot** attach to QEMU-user targets. | Scenario | Works? | Alternative | |----------|--------|-------------| | Native binary (x86_64 on x86_64) | ✅ | - | | Cross-arch under QEMU-user | ❌ | Use on-device frida-server | | Docker native-arch container | ✅ | - | | Docker cross-arch (emulated) | ❌ | Use on-device frida-server | For cross-arch Frida, deploy `frida-server` to the target device: ```bash # On target device: ./frida-server & # On host: frida -H device:27042 -f ./binary -l hook.js --no-pause ``` ### Basic Hook ```javascript // hook_connect.js Interceptor.attach(Module.findExportByName(null, "connect"), { onEnter: function(args) { console.log("[connect] Called"); var sockaddr = args[1]; var family = sockaddr.readU16(); if (family == 2) { // AF_INET var port = sockaddr.add(2).readU16(); var ip = sockaddr.add(4).readByteArray(4); console.log(" Port: " + ((port >> 8) | ((port & 0xff) << 8))); console.log(" IP: " + new Uint8Array(ip).join(".")); } }, onLeave: function(retval) { console.log(" Return: " + retval); } }); ``` ```bash # Run with Frida frida -f ./binary -l hook_connect.js --no-pause ``` ### Tracing All Calls to Library ```javascript // trace_libcurl.js var libcurl = Process.findModuleByName("libcurl.so.4"); if (libcurl) { libcurl.enumerateExports().forEach(function(exp) { if (exp.type === "function") { Interceptor.attach(exp.address, { onEnter: function(args) { console.log("[" + exp.name + "] called"); } }); } }); } ``` ### Memory Inspection ```javascript // dump_memory.js var base = Module.findBaseAddress("binary"); console.log("Base: " + base); // Dump region var data = base.add(0x1000).readByteArray(256); console.log(hexdump(data, { offset: 0, length: 256 })); ``` ## Option D: Docker-Based Cross-Architecture (macOS) **Use Docker for cross-arch execution when native QEMU unavailable.** ### ARM32 Binary on macOS ```bash docker run --rm --platform linux/arm/v7 \ -v ~/code/samples:/work:ro \ arm32v7/debian:bullseye-slim \ sh -c ' # Fix linker path mismatch (common issue) ln -sf /lib/ld-linux-armhf.so.3 /lib/ld-linux.so.3 2>/dev/null || true # Install dependencies if needed (check rabin2 -l output) apt-get update -qq && apt-get install -qq -y libcap2 libacl1 2>/dev/null # Run with library debug output (strace alternative) LD_DEBUG=libs /work/binary args ' ``` ### ARM64 Binary on macOS ```bash docker run --rm --platform linux/arm64 \ -v ~/code/samples:/work:ro \ arm64v8/debian:bullseye-slim \ sh -c 'LD_DEBUG=libs /work/binary args' ``` ### x86 32-bit Binary on macOS ```bash docker run --rm --platform linux/i386 \ -v ~/code/samples:/work:ro \ i386/debian:bullseye-slim \ sh -c '/work/binary args' ``` ### Tracing Limitations in Docker/QEMU User-Mode | Method | Works? | Alternative | |--------|--------|-------------| | strace | ❌ (ptrace not implemented) | `LD_DEBUG=files,libs` | | ltrace | ❌ (same reason) | Direct observation or Frida | | gdb | ✓ (with QEMU `-g` flag) | N/A | ### LD_DEBUG Options (strace alternative) ```bash LD_DEBUG=libs # Library search and loading LD_DEBUG=files # File operations during loading LD_DEBUG=symbols # Symbol resolution LD_DEBUG=bindings # Symbol binding details LD_DEBUG=all # Everything (verbose) ``` --- ## Option E: On-Device Analysis **When emulation fails or device-specific behavior needed.** ### Remote GDB via gdbserver ```bash # On target device (via SSH/ADB) gdbserver :1234 ./binary # On host (with port forward) ssh -L 1234:localhost:1234 user@device & gdb-multiarch -q \ -ex "target remote localhost:1234" \ ./binary ``` ### Remote strace (if available) ```bash # On target device strace -f -o /tmp/trace.log ./binary # Pull log scp user@device:/tmp/trace.log . ``` ## Sandbox Configuration ### Minimal Sandbox (nsjail) ```bash nsjail \ --mode o \ --chroot /sysroot \ --user 65534 \ --group 65534 \ --disable_clone_newnet \ --rlimit_as 512 \ --time_limit 60 \ -- /binary ``` ### QEMU with Resource Limits ```bash # CPU time limit timeout 60 qemu-arm -L /sysroot -strace ./binary # Memory limit via cgroup (requires setup) cgexec -g memory:qemu_sandbox qemu-arm -L /sysroot ./binary ``` ## Anti-Analysis Detection Before dynamic analysis, check for common anti-debugging/anti-analysis patterns: ### Static Detection (Pre-Execution) ```bash # Check for anti-debug strings/imports strings -a binary | grep -Ei 'ptrace|anti|debugger|seccomp|LD_PRELOAD|/proc/self' # r2: Look for ptrace/prctl/seccomp imports r2 -q -c 'iij' binary | jq '.[].name' | grep -Ei 'ptrace|prctl|seccomp' # Common anti-analysis indicators: # - ptrace(PTRACE_TRACEME) - Prevent debugger attach # - prctl(PR_SET_DUMPABLE, 0) - Prevent core dumps # - seccomp - Syscall filtering # - /proc/self/status checks - Detect TracerPid ``` ### Runtime Detection ```bash # If native execution possible: strace -f ./binary 2>&1 | grep -E 'ptrace|prctl|seccomp|/proc/self' ``` ### Mitigation Strategies | Pattern | Detection | Bypass | |---------|-----------|--------| | `ptrace(TRACEME)` | Returns EPERM if debugger attached | Patch call to NOP, use QEMU | | `/proc/self/status` check | Reads TracerPid field | Use QEMU (no /proc emulation) | | Timing checks | `gettimeofday`/`rdtsc` loops | Single-step with GDB, patch checks | | Self-checksum | Reads own binary/memory | Compute expected checksum, patch | **When anti-analysis detected:** Prefer QEMU-strace over GDB (fewer detection vectors), or patch checks in r2 before execution. --- ## Error Recovery | Error | Cause | Solution | |-------|-------|----------| | `Unsupported syscall` | QEMU limitation | Try Qiling or on-device | | `Invalid ELF image` | Wrong arch/sysroot | Verify `file` output | | `Segfault at 0x0` | Missing library | Check `ldd` equivalent | | `QEMU hangs` | Blocking on I/O | Add timeout, check strace | | `Anti-debugging` | Detection code | Use Frida stalker mode | | `exec format error` in Docker | binfmt not registered | Run `tonistiigi/binfmt --install arm` | | `ld-linux.so.3 not found` | Linker path mismatch | Create symlink in container | | `libXXX.so not found` | Missing dependency | `apt install` in container | | Empty mount in Docker | Colima /tmp issue | Use `~/` path instead of `/tmp/` | | `ptrace: Operation not permitted` | strace in QEMU | Use `LD_DEBUG` instead | ## Output Format Record observations as structured data: ```json { "experiment": { "id": "exp_001", "method": "qemu_strace", "command": "qemu-arm -L /usr/arm-linux-gnueabihf -strace ./binary", "duration_secs": 12, "exit_code": 0 }, "syscall_summary": { "network": { "socket": 2, "connect": 1, "send": 5, "recv": 3 }, "file": { "openat": 4, "read": 12, "close": 4 } }, "network_connections": [ { "family": "AF_INET", "address": "192.168.1.100", "port": 8443, "protocol": "tcp" } ], "files_accessed": [ {"path": "/etc/config.json", "mode": "read"}, {"path": "/var/log/app.log", "mode": "write"} ], "hypotheses_tested": [ { "hypothesis_id": "hyp_001", "result": "confirmed", "evidence": "connect() to 192.168.1.100:8443 observed" } ] } ``` ## Knowledge Journaling After dynamic analysis, record findings for episodic memory: ``` [BINARY-RE:dynamic] {filename} (sha256: {hash}) Execution method: {qemu-strace|qemu-gdb|frida|on-device} DECISION: Approved execution with {sandbox_config} (rationale: {why_safe}) Runtime observations: FACT: Binary reads {path} (source: strace openat) FACT: Binary connects to {ip}:{port} (source: strace connect) FACT: Binary writes to {path} (source: strace write) FACT: Function {addr} receives args {values} at runtime (source: gdb) Syscall summary: Network: {socket|connect|send|recv counts} File: {open|read|write|close counts} Process: {fork|exec|clone counts} HYPOTHESIS UPDATE: {confirmed or refined theory} (confidence: {new_value}) Confirmed by: {runtime observation} Contradicted by: {if any} New questions: QUESTION: {runtime-discovered unknown} Answered questions: RESOLVED: {question} → {runtime evidence} ``` ### Example Journal Entry ``` [BINARY-RE:dynamic] thermostat_daemon (sha256: a1b2c3d4...) Execution method: qemu-strace DECISION: Approved execution with network-blocked sandbox (rationale: static analysis shows outbound only, no server) Runtime observations: FACT: Binary reads /etc/thermostat.conf at startup (source: strace openat) FACT: Binary attempts connect to 93.184.216.34:443 (source: strace connect) FACT: Binary writes to /var/log/thermostat.log (source: strace openat O_WRONLY) FACT: sleep(30) called between network attempts (source: strace nanosleep) Syscall summary: Network: socket(2), connect(1-blocked), send(0), recv(0) File: openat(4), read(12), write(8), close(4) Process: none HYPOTHESIS UPDATE: Telemetry client confirmed - reads config, attempts HTTPS to thermco servers every 30s (confidence: 0.95) Confirmed by: connect() to expected IP, sleep(30) timing, config file read Contradicted by: none Answered questions: RESOLVED: "Does it actually phone home?" → Yes, connect() to 93.184.216.34:443 observed RESOLVED: "What files does it access?" → /etc/thermostat.conf (read), /var/log/thermostat.log (write) ``` ## Next Steps → `binary-re-synthesis` to compile findings into report → Additional static analysis if new functions identified → Repeat with different inputs if behavior varies --- Source attribution: David-Li0406 Original project: https://github.com/David-Li0406/meta-skill-evloving/blob/ca3a335628981df10c36e00cb9850df2c247ab9a/skill-flow/data/skills-refined-36k/skillsmp/binary-re/dynamic-analysis/SKILL.md License: Apache-2.0 License information: https://www.apache.org/licenses/LICENSE-2.0 Original upstream instructions; downloaded from Dave AI. ## Upstream license notice Apache License Version 2.0, January 2004 http://www.apache.org/licenses/ TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 1. 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See the License for the specific language governing permissions and limitations under the License. # Dave AI resource metadata Creator / publisher: David-Li0406 Original project: https://github.com/David-Li0406/meta-skill-evloving/blob/ca3a335628981df10c36e00cb9850df2c247ab9a/skill-flow/data/skills-refined-36k/skillsmp/binary-re/dynamic-analysis/SKILL.md Attribution basis: Source repository record Fields of work: Development & Engineering Roles: Backend Developer, Data Engineer, DevOps / SRE, QA / Test Engineer, Security Engineer Specialties: Backend, Testing Tools: Frida, Gdb, Qemu, Strace Country applicability: Country not specified Classification basis: Source catalog labels Instruction SHA-256: c4de4d1bb026f1f7fe9cc489763f3c9119f39c7be47bd932e0d3ed4b20a7ce2d