From 7d8ea1e2c914031cdb52ea86e02081245fc5230f Mon Sep 17 00:00:00 2001
From: Christine Dodrill <me@christine.website>
Date: Mon, 21 Oct 2019 15:30:02 -0400
Subject: [PATCH] blog: OVE-20191021-0001 (#88)

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+---
+title: "OVE-20191021-0001"
+date: "2019-10-21"
+tags:
+ - security
+ - release
+ - javascript
+ - mysql
+ - oh-dear-god
+---
+
+# OVE-20191021-0001
+
+## Within Security Advisory
+
+Multiple vulnerabilities in the mysqljs API and code.
+
+Security Warning Level: yikes/10
+
+## Summary
+
+There are multiple issues exploitable by local and remote actors in
+[mysqljs][mysqljs]. These can cause application data leaks, database leaks, SQL
+injections, arbitrary code execution, and credential leaks among other things.
+
+Mysqljs is unversioned, so it is very difficult to impossible to tell how many
+users are affected by this and what users can do in order to ensure they are
+patched against these critical vulnerabilities.
+
+## Background
+
+Mysqljs is a library intended to facilitate prototyping web applications and
+mobile applications using technologies such as [PhoneGap][phonegap] or
+[Cordova][cordova]. These technologies allow developers to create a web
+application that gets packaged and presented to users as if it was a native
+application.
+
+This library is intended to help with developers creating persistent storage for
+these applications.
+
+## Issues in Detail
+
+There are at least seven vulnerabilities with this library, each of them will be
+outlined below with a fairly vague level of detail.
+
+### mysql.js is NOT versioned
+
+The only version information I was able to find are the following:
+
+- The `Last-Modified` date of Friday, March 11 2016
+- The `ETag` of `80edc3e5a87bd11:0`
+
+These header values correlate to a vulnerable version of the mysql.js file.
+
+An entire copy of this file is embedded for purposes of explanation:
+
+```
+var MySql = {
+    _internalCallback : function() { console.log("Callback not set")},
+    Execute: function (Host, Username, Password, Database, Sql, Callback) {
+        MySql._internalCallback = Callback;
+        // to-do: change localhost: to mysqljs.com
+        var strSrc = "http://mysqljs.com/sql.aspx?";
+        strSrc += "Host=" + Host;
+        strSrc += "&Username=" + Username;
+        strSrc += "&Password=" + Password;
+        strSrc += "&Database=" + Database;
+        strSrc += "&sql=" + Sql;
+        strSrc += "&Callback=MySql._internalCallback";
+        var sqlScript = document.createElement('script');
+        sqlScript.setAttribute('src', strSrc);
+        document.head.appendChild(sqlScript);
+    }
+}
+```
+
+### Fundamental Operation via Cross-Site Scripting
+
+The code operates by creating a `<script>` element. The Javascript source of
+this script is dynamically generated by the remote API server. This opens the
+door for many kinds of Cross-Site Scripting attacks.
+
+Especially because:
+
+### Credentials Exposed over Plain HTTP
+
+The script works by creating a `<script>` element pointed at a HTTP resource in
+order to facilitate access to the MySQL Server. Line 6 shows that the API server
+in question is being queried over UNENCRYPTED HTTP.
+
+```
+var strSrc = "http://mysqljs.com/sql.aspx?";
+```
+
+### Credentials and SQL Queries Are Not URL-Encoded Before Adding Them to a URL
+
+Credentials and SQL queries are not URL-encoded before they are added to the
+`strSrc` URL. This means that values may include other HTTP parameters that
+could be evaluated, causing one of the two following:
+
+### Potential for SQL Injection from Malformed User Input
+
+It appears this API works by people submitting plain text SQL queries. It is
+likely difficult to write these plain text queries in a way that avoids SQL
+injection attacks.
+
+### Potential for Arbitrary Code Execution
+
+Combined with the previous issues, a SQL injection that inserts arbitrary
+Javascript into the result will end up creating an arbitrary code execution bug.
+This could let an attacker execute custom Javascript code on the page, which may
+have even more disastrous consequences depending on the usage of this library.
+
+### Server-Side Code has Unknown Logging Enabled
+
+This means that user credentials and database results may be logged, stored and
+leaked by the mysql.js API server without user knowledge. The server that is
+running the API server may also do additional logging of database credentials
+and results without user knowledge.
+
+### Encourages Bad Practices
+
+Mysql.js works by its API server dialing out an _UNENCRYPTED_ connection to your
+MySQL server over the internet. This requires exposing your MySQL server to the
+internet. This means that user credentials are vulnerable to anyone who has
+packet capture abilities.
+
+Mysql.js also encourages developers commit database credentials into their
+application source code. Cursory searching of GitHub has found
+[this][leakedcreds]. I can only imagine there are countless other potential
+victims.
+
+## Security Suggestions
+
+- Do not, under any circumstances, allow connections to be made without the use
+  of TLS (HTTPS).
+- Version the library.
+- Offer the source code of the API server to allow users to inspect it and
+  ensure their credentials are not being stored by it.
+- Detail how the IIS server powering this service is configured, proving that it
+  is not keeping unsanitized access logs.
+- Ensure all logging methods sanitize or remove user credentials.
+- URL-encode all values being sent as part of a URL.
+- Do not have your service fundamentally operate as a Cross-Site Scripting
+  attack.
+- Do not, under any circumstances, encourage developers to put database
+  credentials in the source code of front-end web applications.
+
+In summary, we label this a solid yikes/10 in terms of security. It would be
+advisable for current users of this library to re-evaluate the life decisions
+that have lead them down this path.
+
+## GReeTZ
+
+Über thanks to [jadr2ddude][jaden] for helping with identifying the unfortunate
+scope of these massive security issues.
+
+Hyper thanks to [J][j] for coming up with a viable GitHub search for potentially
+affected users.
+
+[mysqljs]: http://www.mysqljs.com/
+[phonegap]: https://phonegap.com/
+[cordova]: https://cordova.apache.org/
+[leakedcreds]: https://github.com/search?utf8=%E2%9C%93&q=%22https%3A%2F%2Fmysqljs.com%2Fmysql.js%22&type=Code
+[jaden]: https://twitter.com/CompuJad
+[j]: https://twitter.com/LombaxJay