Microsoft Security Advisory (954462): Rise in SQL Injection Attacks Exploiting Unverified User Data Input

Published: June 24, 2008 | Updated: June 25, 2008

Microsoft is aware of a recent escalation in a class of attacks targeting Web sites that use Microsoft ASP and ASP.NET technologies but do not follow best practices for secure Web application development. These SQL injection attacks do not exploit a specific software vulnerability, but instead target Web sites that do not follow secure coding practices for accessing and manipulating data stored in a relational database. When a SQL injection attack succeeds, an attacker can compromise data stored in these databases and possibly execute remote code. Clients browsing to a compromised server could be forwarded unknowingly to malicious sites that may install malware on the client machine.

Mitigating Factors:

This vulnerability is not exploitable in Web applications that follow generally accepted best practices for secure Web application development by verifying user data input.

Purpose of Advisory: To assist administrators with identifying and correcting vulnerable ASP and ASP.NET Web application code which does not follow best practices for secure Web application development.

Advisory Status: Microsoft Security Advisory and associated tools were released.

Recommendation: Review the suggested actions and configure as appropriate. It is also suggested that server administrators evaluate the effectiveness of the discussed tools and utilize them as needed.

This advisory discusses the following software: Microsoft ASP and ASP.NET technologies.

Suggested Actions

Microsoft has identified several tools to assist administrators. These tools cover detection, defense, and identifying possible coding which may be exploited by an attacker.

• Detection – HP Scrawlr

Hewlett Packard has developed a free scanner which can identify whether sites are susceptible to SQL injection. This tool and support for its use can be found at Finding SQL Injection with Scrawlr at the HP Security Center.

Detailed description:
The tool will be a black-box analysis tool (i.e. no source code required). The user will input a starting URL, and the tool will:

• Recursively crawl that URL for hyperlinks in order to build up a site tree.

• Test all discovered links for verbose SQL injection by sending HTTP requests containing SQL injection attack strings in querystring parameters.

• Examine the HTTP responses from the server for SQL error messages that would indicate a SQL injection vulnerability.

• Report any pages found to be vulnerable to the user, along with the associated input field(s). For example, the tool might report that the fields “username” and “password” on page “foo.asp” are vulnerable.

• Defense – UrlScan version 3.0 Beta

UrlScan version 3.0 Beta is a Microsoft security tool that restricts the types of HTTP requests that Internet Information Services (IIS) will process. By blocking specific HTTP requests, UrlScan helps prevent potentially harmful requests from reaching the Web application on the server. UrlScan 3.0 will install on IIS 5.1 and later, including IIS 7.0. UrlScan 3.0 can be found at URLScan Tool 3.0 Beta.

Detailed Description:
UrlScan version 3.0 is a tool that will allow you to implement many different rules to better protect Web applications on servers from SQL injection attacks. These features include:

• The ability to implement deny rules applied independently to a URL, query string, all headers, a particular header, or any combination of these.

• A global DenyQueryString section that lets you add deny rules for query strings, with the option of checking un-escaped version of the query string as well.

• The ability to use escape sequences in the deny rules to deny CRLF and other non-printable character sequences in configuration.

• Multiple UrlScan instances can be installed as site filters, each with its own configuration and logging options (urlscan.ini).

• Configuration (urlscan.ini) change notifications will be propagated to worker processes without having to recycle them. Log settings are an exception to this.

• Enhanced logging to give descriptive configuration errors.

• Identifying – Microsoft Source Code Analyzer for SQL Injection

A SQL Source Code Analysis Tool has been developed. This tool can be used to detect ASP code susceptible to SQL injection attacks. This tool can be found in Microsoft Knowledge Base Article 954476.

Detailed Description:

The Microsoft Source Code Analyzer for SQL Injection is a standalone tool customers can run on their own ASP source code. In addition to the tool itself, there is documentation included on ways to fix the problems it finds in the code it analyzes. Some key features of this tool are:

• Scans ASP source code for code that can lead to SQL Injection vulnerabilities.

• Generates an output that displays the coding issue.

• This tool only identifies vulnerabilities in classic ASP code. It does not work on ASP.NET code.

Full Advisory/source: Microsoft TechNet

Note: these SQL Injection Attacks have to be considered as extremely dangerous.
Smokey