vulnerability / NVI-00016027 / Revision 1
picklescan vulnerable to arbitrary file create using logging.FileHandler
GitHub lists this reviewed advisory for picklescan. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
picklescan
source listed< 1.0.1
### Summary Unsafe pickle deserialization allows unauthenticated attackers to perform Arbitrary File Creation. By chaining the logging.FileHandler class, an attacker can bypass RCE-focused blocklists to create empty files on the server. The vulnerability allows creating zero-byte files in arbitrary locations but does not permit overwriting or modifying existing files. ### Details The application deserializes untrusted pickle data. While RCE keywords may be blocked, the exploit abuses standard library features: logging.FileHandler: The exploit instantiates this class using its default behavior (append mode). Behavior on Existing Files: If the target file already exists, the handler opens it without modifying its content, resulting in no impact to existing data. Behavior on Non-Existent Files: If the target file does not exist, the handler creates a new zero-byte file with the specified name. ### PoC ```python import pickle class WriteFile: def __reduce__(self): from logging import FileHandler return (FileHandler, ('evil.log',)) with open("bypass_write.pkl", "wb") as f: pickle.dump(WriteFile(), f) handler = pickle.loads(pickle.dumps(WriteFile())) `
03 / Response
What to do next
- investigate
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04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
05 / Provenance
Sources you can inspect
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- GHSA-m7j5-r2p5-c39r ↗
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Public revision history
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- Revision 1 ·
First indexed by Null; source disclosure date is shown separately.