Fastjson 1.2.60 and Earlier Remote Code Execution Vulnerability Threat Alert

Fastjson 1.2.60 and Earlier Remote Code Execution Vulnerability Threat Alert

October 2, 2019 | Mina Hao

1 Vulnerability Description

On September 18, a security researcher submitted Fastjson remediation code on Alibaba’s official GitHub to prevent new exploits of the Fastjson deserialization remote code execution vulnerability. An attacker could exploit this vulnerability to remotely execute malicious code to compromise the server.

Fastjson is an open-source JSON library developed by Alibaba to parse JOSN strings. It can be used to serialize JavaBean into a JSON string and deserialize a JSON string to JavaBean. Fastjson works efficiently and therefore is widely used. Users should take preventive measures as soon as possible.

Reference:

https://github.com/alibaba/fastjson/commit/05a7aa7f748115018747f7676fd2aefdc545d17a

2 Scope of Impact

Affected Versions

Fastjson 1.2.60 and earlier

Unaffected Versions

None

3 Mitigation

Workarounds

Currently, there has been no official release to fix this vulnerability. Affected users must make sure that they have upgraded to the latest version and should disable the AutoType function (disabled by default) to protect against this vulnerability.

Users can disable the AutoType function in either of the following ways:

  • Find the following code in the source code and delete it:

ParserConfig.getGlobalInstance().setAutoTypeSupport(true);

  • When enabling Fastjson on a Java virtual machine, remember not to add the following parameter:

-Dfastjson.parser.autoTypeSupport=true

Once an official security update is released, affected users should apply it as soon as possible to protect against this vulnerability.

Statement

This advisory is only used to describe a potential risk. NSFOCUS does not provide any commitment or promise on this advisory. NSFOCUS and the author will not bear any liability for any direct and/or indirect consequences and losses caused by transmitting and/or using this advisory. NSFOCUS reserves all the rights to modify and interpret this advisory. Please include this statement paragraph when reproducing or transferring this advisory. Do not modify this advisory, add/delete any information to/from it, or use this advisory for commercial purposes without permission from NSFOCUS.

About NSFOCUS

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