Insecure CMap Cache Deserialization in pdfminer.six

This repository is a small standalone Python exploit generator consisting of a README and one executable script, exploit.py. The script does not directly attack a remote service over HTTP; instead, it creates two files intended for use against a vulnerable server-side PDF processing pipeline. First, it serializes a Python object whose __reduce__ method causes os.system to execute a bash reverse shell command, then compresses that pickle into sh.pickle.gz. Second, it builds a minimal PDF file, trigger.pdf, whose font Encoding field is manipulated to contain a hex-escaped server-side filesystem path pointing to the expected pickle location under the upload directory. The apparent exploitation chain is: upload or place the malicious pickle in a directory accessible to the target application, then cause the application to process trigger.pdf with a vulnerable pdfminer-based workflow that interprets the crafted Encoding path and subsequently loads/deserializes the gzip-compressed pickle. Successful exploitation yields remote code execution and a reverse shell to the attacker-supplied LHOST and LPORT. Repository structure is minimal: README.md only gives usage guidance and notes that the upload directory may need to be changed; exploit.py contains all exploit logic, including argument parsing, payload construction, PDF generation, and output of the two artifacts. The exploit is operational rather than a mere proof of concept because it includes a working payload, but it is not framework-based and requires manual targeting details such as the correct upload directory and a vulnerable target workflow.

This repository is a small standalone Python proof-of-concept exploit consisting of one code file (exploit.py) and a minimal README. The script generates two artifacts: (1) sh.pickle.gz, a gzip-compressed Python pickle whose deserialization triggers os.system, and (2) trigger.pdf, a crafted PDF whose font Encoding field is set to a hex-encoded absolute server-side path. The intended attack chain is that a vulnerable pdfminer-based application processes the PDF, derives or accesses a cache/object path based on the attacker-controlled Encoding value, and then loads the attacker-written pickle from the target upload directory. Upon deserialization, the payload runs a bash reverse shell using /dev/tcp to connect back to the supplied LHOST and LPORT. The exploit is operational but not highly flexible: it hardcodes the payload filename as sh and defaults the target directory to /var/www/research.bedside.htb/uploads, though this can be overridden via a third command-line argument. Repository structure is minimal and purpose-built for exploitation rather than detection or research automation.