A flaw was found in the Apache Commons BeanUtils, where the class property in PropertyUtilsBean is not suppressed by default. This flaw allows an attacker to access the classloader.

Improper Access Control vulnerability in Apache Commons.

Improper Access Control vulnerability in Apache Commons.

A special BeanIntrospector class was added in version 1.9.2. This can be used to stop attackers from using the declared class property of Java enum objects to get access to the classloader. However this protection was not enabled by default. PropertyUtilsBean (and consequently BeanUtilsBean) now disallows declared class level property access by default.

Releases 1.11.0 and 2.0.0-M2 address a potential security issue when accessing enum properties in an uncontrolled way. If an application using Commons BeanUtils passes property paths from an external source directly to the getProperty() method of PropertyUtilsBean, an attacker can access the enum’s class loader via the “declaredClass” property available on all Java “enum” objects. Accessing the enum’s “declaredClass” allows remote attackers to access the ClassLoader and execute arbitrary code. The same issue exists with PropertyUtilsBean.getNestedProperty(). Starting in versions 1.11.0 and 2.0.0-M2 a special BeanIntrospector suppresses the “declaredClass” property. Note that this new BeanIntrospector is enabled by default, but you can disable it to regain the old behavior; see section 2.5 of the user's guide and the unit tests.

This issue affects Apache Commons BeanUtils 1.x before 1.11.0, and 2.x before 2.0.0-M2.Users of the artifact commons-beanutils:commons-beanutils

1.x are recommended to upgrade to version 1.11.0, which fixes the issue.

Users of the artifact org.apache.commons:commons-beanutils2

2.x are recommended to upgrade to version 2.0.0-M2, which fixes the issue.

Apache Commons BeanUtils, as distributed in lib/commons-beanutils-1.8.0.jar in Apache Struts 1.x through 1.3.10 and in other products requiring commons-beanutils through 1.9.2, does not suppress the class property, which allows remote attackers to "manipulate" the ClassLoader and execute arbitrary code via the class parameter, as demonstrated by the passing of this parameter to the getClass method of the ActionForm object in Struts 1.

ActionForm in Apache Software Foundation (ASF) Struts before 1.2.9 with BeanUtils 1.7 allows remote attackers to cause a denial of service via a multipart/form-data encoded form with a parameter name that references the public getMultipartRequestHandler method, which provides further access to elements in the CommonsMultipartRequestHandler implementation and BeanUtils.

It was found that commons-beanutils exposes the class property by default, with no mechanism to disable access to it. If a framework built on commons-beanutils does not otherwise suppress access to the class property, then a remote attacker could use this flaw to manipulate the ClassLoader used by the underlying container. This could lead to remote code execution under certain conditions.