GHSA-mw36-7c6c-q4q2

Опубликовано: 16 нояб. 2020

Источник: github

Github: Прошло ревью

CVSS3: 8

Описание

XStream can be used for Remote Code Execution

Impact

The vulnerability may allow a remote attacker to run arbitrary shell commands only by manipulating the processed input stream.

Patches

If you rely on XStream's default blacklist of the Security Framework, you will have to use at least version 1.4.14.

Workarounds

No user is affected, who followed the recommendation to setup XStream's Security Framework with a whitelist! Anyone relying on XStream's default blacklist can immediately switch to a whilelist for the allowed types to avoid the vulnerability.

Users of XStream 1.4.13 or below who still want to use XStream default blacklist can use a workaround depending on their version in use.

Users of XStream 1.4.13 can simply add two lines to XStream's setup code:

xstream.denyTypes(new String[]{ "javax.imageio.ImageIO$ContainsFilter" }); xstream.denyTypes(new Class[]{ java.lang.ProcessBuilder.class });

Users of XStream 1.4.12 to 1.4.7 who want to use XStream with a black list will have to setup such a list from scratch and deny at least the following types: javax.imageio.ImageIO$ContainsFilter, java.beans.EventHandler, java.lang.ProcessBuilder, java.lang.Void and void.

xstream.denyTypes(new String[]{ "javax.imageio.ImageIO$ContainsFilter" }); xstream.denyTypes(new Class[]{ java.lang.ProcessBuilder.class, java.beans.EventHandler.class, java.lang.ProcessBuilder.class, java.lang.Void.class, void.class });

Users of XStream 1.4.6 or below can register an own converter to prevent the unmarshalling of the currently know critical types of the Java runtime. It is in fact an updated version of the workaround for CVE-2013-7285:

xstream.registerConverter(new Converter() { public boolean canConvert(Class type) { return type != null && (type == java.beans.EventHandler.class || type == java.lang.ProcessBuilder.class || type == java.lang.Void.class || void.class || type.getName().equals("javax.imageio.ImageIO$ContainsFilter") || Proxy.isProxy(type)); } public Object unmarshal(HierarchicalStreamReader reader, UnmarshallingContext context) { throw new ConversionException("Unsupported type due to security reasons."); } public void marshal(Object source, HierarchicalStreamWriter writer, MarshallingContext context) { throw new ConversionException("Unsupported type due to security reasons."); } }, XStream.PRIORITY_LOW);

Credits

Chen L found and reported the issue to XStream and provided the required information to reproduce it. He was supported by Zhihong Tian and Hui Lu, both from Guangzhou University.

References

See full information about the nature of the vulnerability and the steps to reproduce it in XStream's documentation for CVE-2020-26217.

For more information

If you have any questions or comments about this advisory:

Open an issue in XStream
Contact us at XStream Google Group

Ссылки

Пакеты

Наименование

com.thoughtworks.xstream:xstream

maven

Затронутые версииВерсия исправления

<= 1.4.13

1.4.14-java7

EPSS

Процентиль: 100%

0.93566

Критический

8 High

CVSS3

CVE ID

CVE-2020-26217

Дефекты

CWE-78

Связанные уязвимости

CVE-2020-26217

CVSS3: 8

ubuntu

около 5 лет назад

XStream before version 1.4.14 is vulnerable to Remote Code Execution.The vulnerability may allow a remote attacker to run arbitrary shell commands only by manipulating the processed input stream. Only users who rely on blocklists are affected. Anyone using XStream's Security Framework allowlist is not affected. The linked advisory provides code workarounds for users who cannot upgrade. The issue is fixed in version 1.4.14.