Multiple vulnerabilities in Apache Struts

Published: 2020-08-14

Risk	High
Patch available	YES
Number of vulnerabilities	2
CVE-ID	CVE-2019-0230 CVE-2019-0233
CWE-ID	CWE-94 CWE-284
Exploitation vector	Network
Public exploit	Public exploit code for vulnerability #1 is available.
Vulnerable software Subscribe	Apache Struts Server applications / Frameworks for developing and running applications
Vendor	Apache Foundation

Security Bulletin

This security bulletin contains information about 2 vulnerabilities.

1) Code Injection

EUVDB-ID: #VU45703

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 - Improper Control of Generation of Code ('Code Injection')

Exploit availability: Yes

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

External links

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

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.

2) Improper access control

EUVDB-ID: #VU45702

Risk: Medium

CVSSv3.1: 5.7 [CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2019-0233

CWE-ID: CWE-284 - Improper Access Control

Exploit availability: No

Description

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due stack-accessible values (e.g. Action properties) of type java.io.File and java.nio.File as well as other classes from these standard library packages are not properly protected by the framework. When a file upload is performed to an Action that exposes the file with a getter, an attacker may manipulate the request such that the working copy of the uploaded file is set to read-only. As a result, subsequent actions on the file will fail with an error. It might also be possible to set the Servlet container's temp directory to read only, such that subsequent upload actions will fail.