B318.md

Pattern: Use of insecure xml.dom.minidom module

Issue: -

Description

This module is not secure against maliciously constructed data. Use defusedxml package instead.

The results of an attack on a vulnerable XML library can be fairly dramatic. With just a few hundred Bytes of XML data an attacker can occupy several Gigabytes of memory within seconds. An attacker can also keep CPUs busy for a long time with a small to medium size request. Under some circumstances it is even possible to access local files on your server, to circumvent a firewall, or to abuse services to rebound attacks to third parties.

This rule checks for the following calls:

• xml.dom.minidom.parse
• xml.dom.minidom.parseString

Example of insecure code:

from xml.dom.minidom import parse as badParse

result = badParse("somfilethatdoesntexist.xml")
print(result)

Example of secure code:

from defusedxml.minidom import parse as goodParse

result = goodParse("somefilethatdoesntexist.xml")
print(result)

Further Reading

• The Python Standard Library - xml.dom.minidom
• GitHub - defusedxml
• Bandit - B318: xml_bad_minidom