Action Message Format (AMF3) Java implementations are vulnerable to insecure deserialization and XML external entities references

Overview

Several Java implementations of AMF3 are vulnerable to insecure deserialization and XML external entities references.

Description

Several Java implementations of Action Message Format (AMF3) are vulnerable to one or more of the following implementation errors:

CWE-502: Deserialization of Untrusted Data

Some Java implementations of AMF3 deserializers derive class instances from java.io.Externalizable rather than the AMF3 specification’s recommendation of flash.utils.IExternalizable. A remote attacker with the ability to spoof or control an RMI server connection may be able to send serialized Java objects that execute arbitrary code when deserialized.

The reporter has identified the following products and versions as being affected, and CVE ID have been assigned as follows:
- Atlassian JIRA, versions from 4.2.4 prior to version 6.3.0 - CVE-2017-5983
- Flamingo amf-serializer by Exadel, version 2.2.0 - CVE-2017-3201
- GraniteDS, version 3.1.1.GA - CVE-2017-3199
- Pivotal/Spring spring-flex - CVE-2017-3203
- WebORB for Java by Midnight Coders, version 5.1.1.0 - CVE-2017-3207

Products using these libraries may also be impacted.

CWE-913: Improper Control of Dynamically-Managed Code Resources

Some Java implementations of AMF3 deserializers may allow instantiation of arbitrary classes via their public parameter-less constructor and subsequently call arbitrary Java Beans setter methods. The ability to exploit this vulnerability depends on the availability of classes in the class path that make use of deserialization. A remote attacker with the ability to spoof or control information may be able to send serialized Java objects with pre-set properties that result in arbitrary code execution when deserialized.

The reporter has identified the following products and versions as being affected, and CVE ID have been assigned as follows:
- Flamingo amf-serializer by Exadel, version 2.2.0 - CVE-2017-3202
- Flex BlazeDS , versions 4.6.0.23207 and 4.7.2 - CVE-2017-5641
- GraniteDS, version 3.1.1.GA - CVE-2017-3200

Products using these libraries may also be impacted.

CWE-611: Improper Restriction of XML External Entity Reference (‘XXE’)

Some Java implementations of AMF3 deserializers allow external entity references (XXEs) from XML documents embedded within AMF3 messages. If the XML parsing is handled incorrectly it could potentially expose sensitive data on the server, denial of service, or server side request forgery.

- Flamingo amf-serializer by Exadel, version 2.2.0 - CVE-2017-3206
- Flex BlazeDS , version 4.6.0.23207 - CVE-2015-3269
- GraniteDS, version 3.1.1.GA - CVE-2016-2340 (see VU#279472)
- WebORB for Java by Midnight Coders, version 5.1.1.0 - CVE-2017-3208

Products using these libraries may also be impacted.

More information is provided in the researcher’s advisory.

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Impact

A remote attacker with the ability to spoof or control a server connection may be able to send serialized Java objects that execute arbitrary code when deserialized.

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Solution

Apply an update if available

CERT/CC recommends applying an update or patch to your product if available. Some vendors have responded that only out-of-support versions of products are impacted. In these cases, CERT/CC recommends updating your product to the latest supported version.

More details are included for each vendor in the vendor records below.

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Developers should use an updated JDK

Developers should use an updated Java development kit (JDK). JDK 8 update 121, JDK 7 update 131 and JDK 6 update 141 implement basic serialization blacklisting filters, while more serialization protection measures are expected in the upcoming Java 9. For more information, please see JEP 290.

Developers should be suspicious of deserialized data from untrusted sources

Developers should in general be very suspicious of deserialized data from an untrusted source. For best practices, see the CERT Oracle Coding Standard for Java guidelines for Serialization, especially rules SER12-J and SER13-J.
**
Use firewall rules or filesystem restrictions**

System administrators may be able to mitigate this issue for some applications by restricting access to the network and/or filesystem. If an affected application utilizes an open port accepting serialized objects, restricting access to the application may help mitigate the issue.

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Vendor Information

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Adobe __ Affected

Notified: March 28, 2017 Updated: April 03, 2017

Statement Date: March 31, 2017

Status

Affected

Vendor Statement

We have not received a statement from the vendor.

Vendor Information

Affected versions (< 4.7) of Adobe Flex BlazeDS are no longer supported. Any affected users should upgrade to a newer version of BlazeDS now supported by the Apache Software Foundation.

Apache Software Foundation __ Affected

Notified: March 28, 2017 Updated: April 07, 2017

Statement Date: April 04, 2017

Status

Affected

Vendor Statement

We have not received a statement from the vendor.

Vendor Information

Apache Flex BlazeDS version 4.7.3 addresses CVE-2017-5641 by restricting classes to only those whitelisted. Affected users are encouraged to upgrade.

The XXE vulnerability (CVE-2015-3269) was previously addressed in version 4.7.1.

Vendor References

• <https://issues.apache.org/jira/browse/FLEX-35290&gt;
• <http://www.apache.org/dyn/closer.lua/flex/BlazeDS/4.7.3/&gt;
• <http://apache-flex-users.2333346.n4.nabble.com/CVE-2015-3269-Apache-Flex-BlazeDS-Insecure-Xml-Entity-Expansion-Vulnerability-td10976.html&gt;
• <https://flex.apache.org/download-blazeds.html&gt;

Atlassian __ Affected

Updated: April 07, 2017

Status

Affected

Vendor Statement

Atlassian has identified that JIRA versions from 4.2.4 prior to version 6.3.0 are impacted. These versions are all currently unsupported.

Vendor Information

Atlassian has released JIRA Security Advisory 2017-03-09 for this issue. CVE-2017-5983 was assigned according to ticket JRA-64077.

Vendor References

• <https://confluence.atlassian.com/display/JIRA063/JIRA+Security+Advisory+2017-03-09&gt;
• <https://jira.atlassian.com/browse/JRA-64077?src=confmacro&gt;

VMware __ Affected

Notified: March 16, 2017 Updated: April 14, 2017

Statement Date: April 14, 2017

Status

Affected

Vendor Statement

We have not received a statement from the vendor.

Vendor Information

VMware uses Flex BlazeDS, and has released security advisory VMSA-2017-0007 to address this issue.

Vendor References

• <https://www.vmware.com/security/advisories/VMSA-2017-0007.html&gt;

Exadel Unknown

Notified: March 28, 2017 Updated: March 28, 2017

Status

Unknown

Vendor Statement

We have not received a statement from the vendor.

Vendor References

Granite Data Services Unknown

Notified: March 16, 2017 Updated: March 16, 2017

Status

Unknown

Vendor Statement

We have not received a statement from the vendor.

Vendor References

Hewlett Packard Enterprise Unknown

Notified: March 28, 2017 Updated: March 28, 2017

Status

Unknown

Vendor Statement

We have not received a statement from the vendor.

Vendor References

Midnight Coders __ Unknown

Notified: March 16, 2017 Updated: April 03, 2017

Statement Date: March 16, 2017

Status

Unknown

Vendor Statement

The demonstrated code would not be able to be able to cause any harm for the reason that calling setAutoCommit( true ) requires a connection object which is not even initialized at that time (see lines 4067-4087 at: <http://www.docjar.com/html/api/com/sun/rowset/JdbcRowSetImpl.java.html>).

Additionally, in our implementation all com.sun.* and java.* classes are excluded from deserialization.

Vendor Information

We are not aware of further vendor information regarding this vulnerability.

Pivotal Unknown

Notified: March 28, 2017 Updated: March 28, 2017

Status

Unknown

Vendor Statement

We have not received a statement from the vendor.

Vendor References

SonicWall Unknown

Notified: March 28, 2017 Updated: March 28, 2017

Status

Unknown

Vendor Statement

We have not received a statement from the vendor.

Vendor References

CVSS Metrics

Group	Score	Vector
Base	9.3	AV:N/AC:M/Au:N/C:C/I:C/A:C
Temporal	8.4	E:POC/RL:U/RC:C
Environmental	6.3	CDP:ND/TD:M/CR:ND/IR:ND/AR:ND

References

• <http://codewhitesec.blogspot.com/2017/04/amf.html&gt;
• <http://openjdk.java.net/jeps/290&gt;
• <http://www.kb.cert.org/vuls/id/279472&gt;
• <http://www.adobe.com/go/amfspec&gt;
• <https://cwe.mitre.org/data/definitions/502.html&gt;
• <https://cwe.mitre.org/data/definitions/913.html&gt;
• <https://cwe.mitre.org/data/definitions/611.html&gt;

Acknowledgements

Thanks to Markus Wulftange for reporting this vulnerability.

This document was written by Garret Wassermann.

Other Information

CVE IDs:	CVE-2015-3269, CVE-2016-2340, CVE-2017-5641, CVE-2017-5983, CVE-2017-3199, CVE-2017-3200, CVE-2017-3201, CVE-2017-3202, CVE-2017-3203, CVE-2017-3206, CVE-2017-3207, CVE-2017-3208
Date Public:	2017-04-04 Date First Published: