AppSec 2007 - .NET Web Services Hacking

.NET Web Services Hacking – Scan, Attacks and Defense Shreeraj Shah Founder & Director, Blueinfy [email_address] 91+987-902-7018

Who am I? Founder & Director Blueinfy Solutions Pvt. Ltd. (Brief) Past experience Net Square, Chase, IBM & Foundstone Interest Web security research Published research Articles / Papers – Securityfocus, O’erilly, DevX, InformIT etc. Tools – wsScanner, scanweb2.0, AppMap, AppCodeScan, wsChess etc. Advisories - .Net, Java servers etc. Books (Author) Hacking Web Services (Thomson 2006) Web Hacking (AWL 2003) Web 2.0 Security (Work in progress) http://shreeraj.blogspot.com [email_address] Tools – http://www.blueinfy.com/tools.html

Founder & Director

Blueinfy Solutions Pvt. Ltd. (Brief)

Past experience

Net Square, Chase, IBM & Foundstone

Interest

Web security research

Published research

Articles / Papers – Securityfocus, O’erilly, DevX, InformIT etc.

Tools – wsScanner, scanweb2.0, AppMap, AppCodeScan, wsChess etc.

Advisories - .Net, Java servers etc.

Books (Author)

Hacking Web Services (Thomson 2006)

Web Hacking (AWL 2003)

Web 2.0 Security (Work in progress)

Agenda Web Services in an era of Web 2.0 .NET Web Services Assessment Methodology Footprinting and Discovery Enumeration, Profiling and Fingerprinting Attack Vectors Scanning and Fuzzing .NET Web Services Defense Methodology Code Scanning & Secure Coding Web Services Firewall (Content Filtering) Conclusion

Web Services in an era of Web 2.0

.NET Web Services Assessment Methodology

Footprinting and Discovery

Enumeration, Profiling and Fingerprinting

Attack Vectors

Scanning and Fuzzing

.NET Web Services Defense Methodology

Code Scanning & Secure Coding

Web Services Firewall (Content Filtering)

Conclusion

Web Services on the rise with Web 2.0 80% of companies are investing in Web Services as part of their Web 2.0 initiative (McKinsey2007 Global Survey) By the end of 2007, 30 percent of large companies will have some kind of Web 2.0-based business initiative up and running. (Gartner) 2008. Web Services or Service-Oriented Architecture (SOA) would surge ahead. (Gartner)

80% of companies are investing in Web Services as part of their Web 2.0 initiative (McKinsey2007 Global Survey)

By the end of 2007, 30 percent of large companies will have some kind of Web 2.0-based business initiative up and running. (Gartner)

2008. Web Services or Service-Oriented Architecture (SOA) would surge ahead. (Gartner)

Web Services and Web 2.0 HTML / JS / DOM RIA (Flash) Ajax Browser Internet Blog Local Application Database Authentication Internet Weather News Documents Emails Bank/Trade RSS feeds Web Services

Widget DOM HTML/CSS JavaScript SOAP XML-RPC JSON XML Open APIs SaaS Services REST Browser Protocols Consuming Web Services Ajax Flash / RIA JSON-RPC Structures Server-Side HTTP(S)

Methodology Footprinting & Discovery Enumeration & Profiling Vulnerability Detection Code / Config Scanning Web Services Firewall Secure Coding Insecure Web Services Secure Web Services Blackbox Whitebox Defense & Countermeasure

Footprinting and Discovery Objective: Discovering Web Services running on application domain. Methods Primary discovery Crawling and spidering Script analysis and page scrubbing Traffic analysis Secondary discovery Search engine queries UDDI scanning

Objective: Discovering Web Services running on application domain.

Methods

Primary discovery

Crawling and spidering

Script analysis and page scrubbing

Traffic analysis

Secondary discovery

Search engine queries

UDDI scanning

Primary Discovery Crawling the application and mapping file extensions and directory structures, like “.asmx” Page scrubbing – scanning for paths and resources in the pages, like atlas back end call to Web Services. Recording traffic while browsing and spidering, look for XML based traffic – leads to XML-RPC, REST, SOAP, JSON calls.

Crawling the application and mapping file extensions and directory structures, like “.asmx”

Page scrubbing – scanning for paths and resources in the pages, like atlas back end call to Web Services.

Recording traffic while browsing and spidering, look for XML based traffic – leads to XML-RPC, REST, SOAP, JSON calls.

Primary Discovery - Demos Page scanning with grep – Look in JavaScripts for URLs, Paths etc. Crawling – Simple! Scanning for Atlas references – Framework creates stubs and proxy. – scanweb2.0/scanatlas Urlgrep can be used as well. Demo

Page scanning with grep – Look in JavaScripts for URLs, Paths etc.

Crawling – Simple!

Scanning for Atlas references – Framework creates stubs and proxy. – scanweb2.0/scanatlas

Urlgrep can be used as well.

Secondary Discovery Searching UDDI server for Web Services running on particular domain. Three tactics for it – business, services or tModel. Running queries against search engines like Google or MSN with extra directives like “inurl” or “filetype” Look for “asmx” wsScanner – Discovery! Demo

Searching UDDI server for Web Services running on particular domain.

Three tactics for it – business, services or tModel.

Running queries against search engines like Google or MSN with extra directives like “inurl” or “filetype”

Look for “asmx”

wsScanner – Discovery!

Enumerating and Profiling Fingerprinting .Net framework and Client side technologies – Dojo or Atlas … Scanning WSDL Looking for Methods Collecting In/Out parameters Security implementations Binding points Method signature mapping Demo

Fingerprinting .Net framework and Client side technologies – Dojo or Atlas …

Scanning WSDL

Looking for Methods

Collecting In/Out parameters

Security implementations

Binding points

Method signature mapping

Risk - In transit In transit Sniffing or Spoofing WS-Routing security concern Replay attacks

In transit Sniffing or Spoofing

WS-Routing security concern

Replay attacks

Risk - Web services Engine Buffer overflow XML parsing attacks Spoiling Schema Complex or Recursive structure as payload Denial of services Large payload

Buffer overflow

XML parsing attacks

Spoiling Schema

Complex or Recursive structure as payload

Denial of services

Large payload

Web services Deployment - Risk Fault code leaks Permissions & Access issues Poor policies Customized error leakage Authentication and Certification

Fault code leaks

Permissions & Access issues

Poor policies

Customized error leakage

Authentication and Certification

Web services User code - Risk Parameter tampering WSDL probing SQL/LDAP/XPATH/OS command injection Virus/Spyware/Malware injection Bruteforce Data type mismatch Content spoofing Session tampering Format string Information leakage Authorization

Parameter tampering

WSDL probing

SQL/LDAP/XPATH/OS command injection

Virus/Spyware/Malware injection

Bruteforce

Data type mismatch

Content spoofing

Session tampering

Format string

Information leakage

Authorization

Scanning strategies Manual invocation and response analysis. Dynamic proxy creation and scanning. Auto auditing for various vectors. Fuzzing Web Services streams – XML or JSON Response analysis is the key Look for fault code nodes Enumerating fault strings Dissecting XML message and finding bits Hidden error messages in JSON Demo

Manual invocation and response analysis.

Dynamic proxy creation and scanning.

Auto auditing for various vectors.

Fuzzing Web Services streams – XML or JSON

Response analysis is the key

Look for fault code nodes

Enumerating fault strings

Dissecting XML message and finding bits

Hidden error messages in JSON

A1 - Cross Site Scripting (XSS) XSS is possible through Web Services. It would be DOM based XSS via eval(). JSON-RPC based stream coming in the browser and get injected into DOM. Source of stream can be of third party and Un-trusted. XML streams coming in the browser and can cause XSS via document.write call. Demo

XSS is possible through Web Services.

It would be DOM based XSS via eval().

JSON-RPC based stream coming in the browser and get injected into DOM.

Source of stream can be of third party and Un-trusted.

XML streams coming in the browser and can cause XSS via document.write call.

A2 - Injection Flaws Web Services methods are consuming parameters coming from end users. It is possible to inject malicious characters into the stream. It can break Web Services code and send faultsting back to an attacker Various injections possible – SQL and XPATH Demo

Web Services methods are consuming parameters coming from end users.

It is possible to inject malicious characters into the stream.

It can break Web Services code and send faultsting back to an attacker

Various injections possible – SQL and XPATH

A3 - Malicious File Execution Malicious command can be injected through the parameter. WS supports attachments as well and that can lead to uploading a file. This can give remote command execution capability to the attacker. Demo

Malicious command can be injected through the parameter.

WS supports attachments as well and that can lead to uploading a file.

This can give remote command execution capability to the attacker.

A4 - Insecure Direct Object Reference Injecting characters to break file system sequences. Faultcode spits out internal information if not protected. Customized error shows the file refernces. Access to internal file and full traversal to directories Inspecting methods and parameters in the profile stage can help. Demo

Injecting characters to break file system sequences.

Faultcode spits out internal information if not protected.

Customized error shows the file refernces.

Access to internal file and full traversal to directories

Inspecting methods and parameters in the profile stage can help.

A5 - Cross Site Request Forgery (CSRF) CSRF with XML streams XML-RPC or SOAP based request can be generated from browsers. Splitting form and XML injection is possible – interesting trick. If Content-Type is not validated on the server then it can cause a potential CSRF. XForms usage in browser can produce XML requests to attack CSRF. Demo

CSRF with XML streams

XML-RPC or SOAP based request can be generated from browsers.

Splitting form and XML injection is possible – interesting trick.

If Content-Type is not validated on the server then it can cause a potential CSRF.

XForms usage in browser can produce XML requests to attack CSRF.

A6 - Information Leakage and Improper Error Handling SOAP based Web Services throws faultcode and faultstrings back to the client. Information can be embedded in it. It try/catch is not well implemented then default error from .NET framework. Published vulnerabilities with leakage information providing references to file, ldap, etc. Demo

SOAP based Web Services throws faultcode and faultstrings back to the client.

Information can be embedded in it.

It try/catch is not well implemented then default error from .NET framework.

Published vulnerabilities with leakage information providing references to file, ldap, etc.

A7 - Broken Authentication and Session Management Web Services are having session management binding. It is possible to have methods supporting session in .NET Session identifier disclosure can lead to hijacking of Web Services SOAP message can be bruteforce as well – poor passwords and multiple trial WS-Security can be used around it

Web Services are having session management binding.

It is possible to have methods supporting session in .NET

Session identifier disclosure can lead to hijacking of Web Services

SOAP message can be bruteforce as well – poor passwords and multiple trial

WS-Security can be used around it

A8/A9 - Insecure Cryptographic and Communication Implementation of WSE security Web Services traffic not going over SSL XML-Security or nodes encryption – if cracked or decrypt Sessions are established on the tokens, goes over wire in clear text Analysis needs to be done in the case of mashup and API calls. Several applications and widgets are making backend API calls in clear text (user/pass)

Implementation of WSE security

Web Services traffic not going over SSL

XML-Security or nodes encryption – if cracked or decrypt

Sessions are established on the tokens, goes over wire in clear text

Analysis needs to be done in the case of mashup and API calls.

Several applications and widgets are making backend API calls in clear text (user/pass)

A10 - Failure to Restrict URL Access In Web Services instead of URL – methods. WSDL scanning and disclosures can weaken the Services. Some internal methods are out in public. Admin APIs can be accessed. These internal methods can be used to attack Web Services.

In Web Services instead of URL – methods.

WSDL scanning and disclosures can weaken the Services.

Some internal methods are out in public.

Admin APIs can be accessed.

These internal methods can be used to attack Web Services.

Code Analysis for Web Services Scanning the code base. Identifying linkages. Method signatures and inputs. Looking for various patterns for SQL, LDAP, XPATH, File access etc. Checking validation on them. Code walking and tracing the base - Key Demo

Scanning the code base.

Identifying linkages.

Method signatures and inputs.

Looking for various patterns for SQL, LDAP, XPATH, File access etc.

Checking validation on them.

Code walking and tracing the base - Key

Regular firewall will not work Content filtering on HTTP will not work either since it is SOAP over HTTP/HTTPS SOAP level filtering and monitoring would require ISAPI level filtering is essential SOAP content filtering through IHTTPModule Code filtering with IHTTPModule

Regular firewall will not work

Content filtering on HTTP will not work either since it is SOAP over HTTP/HTTPS

SOAP level filtering and monitoring would require

ISAPI level filtering is essential

SOAP content filtering through IHTTPModule

IIS Web Server HTTP Stack .Net Web Services IIS Web Server web2wall Web Services Client SOAP Envelope Reject Rules for SOAP Code filtering with IHTTPModule

.Net Web Services .asmx file IIS web server web2wall Web Services Client SOAP Input Envelope <soap:Body soap:encodingStyle=&quot;http://schemas.xmlsoap.org/soap/encoding/&quot;> <q1:getInput xmlns:q1=&quot;http://DefaultNamespace&quot;> <id xsi:type=&quot;xsd:string&quot;>12123</id> </q1:getInput> </soap:Body> DB <id xsi:type=&quot;xsd:string&quot;>12123</id> id=12123 Bal=$2500 <ns1:getInputReturn xsi:type=&quot;xsd:string&quot;> $2500 </ns1:getInputReturn> SOAP Output Envelope Code filtering with IHTTPModule

HTTP Stack for IIS Request IIS aspnet_isapi.dll HttpApplication HttpHandler HttpModule HttpModule HttpModule Response Web Application Resource Web Application Client 146

HTTP Stack HttpRuntime HttpApplicationFactory HttpApplication HttpHandlerFactory HttpContext IHttpModule Handler HttpRequest HttpResponse IHttpHandler 147

HTTP Stack for .Net HttpRuntime HttpApplicationFactory HttpApplication HttpHandlerFactory IHttpModule Handler Web Application Firewall & IDS 148

IHTTPModule for Web Services Firewall Code walkthrough – Events and Hooks Loading the DLL Setting up the rules Up and running! Demo. Demo

Code walkthrough – Events and Hooks

Loading the DLL

Setting up the rules

Up and running!

Demo.

Conclusion Web Services can be vulnerable to various attack vectors. Footprinting and Discovery are start points. Scanning and Auditing can help in finding holes. Fuzzing is also important aspect. Top 10 – OWASP, for Web Services Scanning the code is equally important. Web Services Firewall – Armoring the app.

Web Services can be vulnerable to various attack vectors.

Footprinting and Discovery are start points.

Scanning and Auditing can help in finding holes.

Fuzzing is also important aspect.

Top 10 – OWASP, for Web Services

Scanning the code is equally important.

Web Services Firewall – Armoring the app.

.NET Web Services Hacking – Scan, Attacks and Defense Thanks!