Proof of concept
Do your applications use this vulnerable package?
24 Aug 2021
24 Aug 2021
How to fix?
com.thoughtworks.xstream:xstream to version 1.4.18 or higher.
com.thoughtworks.xstream:xstream is a simple library to serialize objects to XML and back again.
Affected versions of this package are vulnerable to Denial of Service (DoS). This vulnerability may allow a remote attacker to allocate 100% CPU time on the target system depending on CPU type or parallel execution of such a payload resulting in a denial of service only by manipulating the processed input stream. No user is affected, who followed the recommendation to setup XStream's security framework with a whitelist limited to the minimal required types. XStream 1.4.18 uses no longer a blacklist by default, since it cannot be secured for general purpose.
<linked-hash-set> <sun.reflect.annotation.AnnotationInvocationHandler serialization='custom'> <sun.reflect.annotation.AnnotationInvocationHandler> <default> <memberValues class='javax.script.SimpleBindings'> <map class='javax.script.SimpleBindings' reference='..'/> </memberValues> <type>javax.xml.transform.Templates</type> </default> </sun.reflect.annotation.AnnotationInvocationHandler> </sun.reflect.annotation.AnnotationInvocationHandler> </linked-hash-set>
XStream xstream = new XStream(); xstream.fromXML(xml);
Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its intended and legitimate users.
Unlike other vulnerabilities, DoS attacks usually do not aim at breaching security. Rather, they are focused on making websites and services unavailable to genuine users resulting in downtime.
One popular Denial of Service vulnerability is DDoS (a Distributed Denial of Service), an attack that attempts to clog network pipes to the system by generating a large volume of traffic from many machines.
When it comes to open source libraries, DoS vulnerabilities allow attackers to trigger such a crash or crippling of the service by using a flaw either in the application code or from the use of open source libraries.
Two common types of DoS vulnerabilities:
High CPU/Memory Consumption- An attacker sending crafted requests that could cause the system to take a disproportionate amount of time to process. For example, commons-fileupload:commons-fileupload.
Crash - An attacker sending crafted requests that could cause the system to crash. For Example, npm