Vulnerability identifier: #VU45703

Vulnerability risk: High

CVSSv3.1: 9.1 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C]

CVE-ID: CVE-2019-0230

CWE-ID: CWE-94

Exploitation vector: Network

Exploit availability: Yes

Vulnerable software:
Apache Struts
Server applications / Frameworks for developing and running applications

Vendor: Apache Foundation

Description

The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The Apache Struts frameworks, when forced, performs double evaluation of attributes' values assigned to certain tags attributes such as id so it is possible to pass in a value that will be evaluated again when a tag's attributes will be rendered. With a carefully crafted request, this can lead to Remote Code Execution (RCE).

The problem only applies when forcing OGNL evaluation inside a Struts tag attribute, when the expression to evaluate references raw, unvalidated input that an attacker is able to directly modify by crafting a corresponding request.

Example:

<s:url var="url" namespace="/employee" action="list"/><s:a id="%{skillName}" href="%{url}">List available Employees</s:a>

If an attacker is able to modify the skillName attribute in a request such that a raw OGNL expression gets passed to the skillName property without further validation, the provided OGNL expression contained in the skillName attribute gets evaluated when the tag is rendered as a result of the request.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Apache Struts: 2.0.0 - 2.5.20

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External links
http://cwiki.apache.org/confluence/display/WW/S2-059

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability. However, a fully functional exploit for this vulnerability is available.