Protecting Web services and Web applications against security threats

Rix GroenboomSupport Manager, Parasoft UK Ltd

rix.groenboom@parasoft.com

What We Will Explore

What threats we see today Practices for securing Web Services and

SOA Use of a Policy based Approach:

“Inside Out & Outside In”

First, Lets Redefine “SOAP”

SOAP = Service Oriented Architecture Protocol

Experience

Who is responsible for SOA security?

When is SOA security addressed?

What activities are involved in SOA security?

Structure of this presentation

Problems, Threats, and Solutions

“Testing Security Into The Application”

A Four-Step Approach To Securing SOAP

Examples of Threats Prevented

Problems: XML Bomb

bomb.xml

Problems: XML Bomb

<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE SOAP-ENV:Envelope [ <!ELEMENT SOAP-ENV:Envelope ANY> <!ATTLIST SOAP-ENV:Envelope entityReference CDATA #IMPLIED> <!ENTITY x0 "Bomb!"> <!ENTITY x1 "&x0;&x0;"> <!ENTITY x2 "&x1;&x1;"> ... <!ENTITY x20 "&x19;&x19;"> <!ENTITY x21 "&x20;&x20;"> <!ENTITY x22 "&x21;&x21;">]>

Enterprise network protected by firewall

Application is the only way in

Must keep application open for business

User (potential hackers) must have access to the application

What is wrong with this picture ?

Software as a Service: Security Challenges

= Serious Security risks

DatabaseServer

Application Server

Legacy

Presentation Layer

Web Services

Application Logic Thin

ClientWeb Site

Software as a Service: Security Challenges

Web services vulnerabilities can be present in the: Operating system or the applications that ship with it Network Database Web server Application server XML parser or Web services implementation / stack Application code XML appliance

And, yes, that post-it note with the password under your drawer or keyboard…

Software as a Service: Security Challenges

Problems with Web services and SOA Cut through firewall

SOAP messages often travel over HTTP port 80 Business processes on the web

Expose internal APIs to anonymous users New technology, new mistakes

Once web apps are locked tighter, guess who’s next? Implied assumptions, external dependence

“I can’t see it, neither can a hacker” “We can trust that service to work properly” “The use of the service is constrained by the client

application”

The Y2K problem revisited !

Securing Web Services – Solutions So far

General Practices Define acceptable protocols

Shut down other services Lock down firewall (change port)

Enforce security mechanisms Authentication Access Control Auditing … to Z

Securing Web Services – Solutions So far

SOA Security Mechanisms WS-Security

XML Encryption XML Signature X509 Username Tokens SAML

WS-Trust WS-SecureConversation WS-SecurityPolicy WS-Federation WS-Privacy WS-*

General Web Services Threats

Common to all Web applications SQL Injections

Special characters in queries

Capture and Replay Attacks Man in the middle attacks

DoS (resulting from a large load) Blow up application from inside

Improper Error Handling Dump of stack trace etc

Broken Access Control Take over earlier sessions tokens etc

General Web Services Threats

Specific to XML Web services Large Payloads

Send huge XML load, or generate huge responses

XPath Injections Query XML documents for certain nodes

External Entity Attacks Misuse pointed to XML data using URI

XML Bombs Recursive XML entity declaration

General Web Services Threats

However, threats also come from within: Since 1999, the percentage of companies reporting a

computer-security incident from inside is almost the same as those reporting it from the outside

28.9% of of security incidents come from employees

Source: The Wall Street Journal Online (Feb 13, 2006) http://online.wsj.com/article/

SB113926053552466409.html

AuditsAssumptions

Challenge - Properly Addressing Security

Testing security “into” the Web service application: Common “end-of-cycle” security testing can detect some

standard application security vulnerabilities, however… Approaching security merely as a “bug finding” exercise is

inefficient and costly It is impossible to cover all possible execution paths with testing!

GAPNeed to be able to detect vulnerabilities as

early as possible.

Develop Test MonitorArchitect

Why More Testing Does Not Help ?

String username = request.getParameter("USER");String password = request.getParameter("PASSWORD");

An attacker passes ' or 1=1 # for usersname

SELECT user_id FROM UsersWHERE username='' or 1=1 #' AND password=‘foo’

String query = “SELECT user_id FROM Users WHERE username=‘” + username + “’ AND password=‘” + password + “’”;Statement.execute(query);

Securing Web Services

A different approach is needed A preventive, policy-based approach rather

than a reactive one Security, like quality, must be built into the

application and cannot be tested in Application are large and complex

We propose a combined approach: Outside In Inside Out

Securing Web Services: Step 1

Assessment: Impact & Risk Analyze the business process

Assets, users, entry points What needs to be protected? How? Outsource for expertise before implementation

Define security threats CIA: Confidentiality, Availability, Integrity Risk = Threat x Vulnerability x Expected Loss

– Threat = Motivated Attacker with Path to Valuable Asset

– Vulnerability = Weakness in system– Expected Loss = Impact of threat realization

Misusage, the general WS threats, etc.

Securing Web Services: Step 1

Assessment: Penetration Testing Find a few general vulnerabilities Many penetration activities can be automated

Generate injection attacks, XSS, scan for broken access control, etc.

Simulate large loads, generate big messages, etc. Penetration testing is not exhaustive But, a vulnerability you find

Is like a real bug: if you see one, there are 1000 you do not see !

“where smoke is, is fire” Helps you in Step 2

Securing Web Services: Step 2

Develop a Security Policy: A security policy is a set of guidelines that are an overall

strategy for application security

Secure implementation guidelines: Use trusted libraries Adhere to coding and XML standards

Release IO resources in the code Turn off DTD support in XML parsers Constrain schema types

Review implementation for errors Turn off features by default

Securing Web Services: Step 2

However, security policy also covers applications code Key areas that need are required:

Access control and Authentication Denial of Service Command Injection Concurrency Cryptography Error Handling Input Validation Logging Malicious Code Memory and Session Management

Securing Web Services: Step 3

Enforce Security Policy Throughout SDLC A policy without an automated enforcement

mechanisms is like law without police

Available techniques: Static / Dynamic Code analysis

Map policies to executable rules Configure the rules based on the policies and projects

at hand Compliance SOA Development Governance in SDLC

Like: SOAP, WSDL, Schema, XML Metadata. Runtime SOA Governance

Management, Registry, Orchestration

Securing Web Services: Step 4

Regression Testing Software development is an iterative process An iterative development process fails without

regression testing. The same applies to security Fixing a security vulnerability should be coupled

with a policy and an enforcement mechanism to prevent it from reoccurring again

Regression testing practices results in a visible quality process that reinforces trust

General Web Services Threats Prevented

SQL Injections Policy: Validate user input; strip potentially malicious

characters like ‘ and “ as soon as you get them Test: Penetrate, regression test

Capture and Replay Attacks Policy: Use signed random nonce values and

Timestamps Test: Penetrate, regression test

DoS (resulting from a large load) Policy: Secure coding standards Test: Simulate attacks, regression test

General Web Services Threats Prevented

Improper Error Handling Policy: Catch/handle all exceptions Test: Penetrate, regression test

Broken Access Control Policy: Baseline/extended security policies Test: Positive & negative conditions,

regression test Large Payloads

Policy: Constrain schema types Test: Simulate attacks, regression test

General Web Services Threats Prevented

XPath Injections Policy: Validate user input at the entry

point Test: Simulate attacks, regression test

External Entity Attacks Policy: Disable DTD processing in XML parser Test: Simulate attacks, regression test

XML Bombs Policy: Disable DTD processing in XML

parser Test: Simulate attacks, regression test

Securing Web Services

Old tricks for new dogs… Start from the beginning Assume the worst Use standards rather than “build your own” Be proactively consistent Consider external and internal threats Develop and enforce a security policy

Compliance Vs. Audit “Build it in”, not “test it in”

Company; Corporate Background

Founded in 1987, privately held

300+ employees worldwide

Headquarters in Monrovia, CA

10,000 customers worldwide

ABN AMRO, AXA, Bank of America, Bloomberg, Boeing, Cisco, DCA, Disney, HP, IBM, Lehman Brothers, Lockheed, Northrop, Panasonic UK, Philips, P&O Ferries, Royal Bank of Scotland

Technical innovator

Fifteen US patents for software technology

                                                              

Conclusion

Thank you

Resources http://www.cgisecurity.com/ws/ http://www.oasis-open.org/committees/

tc_cat.php?cat=ws http://www.soaleaders.org/

Commercial http://www.parasoft.com/

Questions?