securing applications

Securing ApplicationsSecuring ApplicationsA Practical Primer for DevelopersA Practical Primer for Developers

Burak DayıoğluBurak Dayıoğlu

Your security, your future

© 2009, Pro-G Information Security & Research Ltd., All Rights Reserved

About the presenterAbout the presenter


Application Security TodayApplication Security Today

BJ's Settles Case with FTC over Customer Data

JUNE 17, 2005 -- After credit card data for thousands of customers was used to make fraudulent purchases in other stores, BJ's Wholesale Club Inc. has agreed

FTC alleges weak security at wholesale club led to fraudulent sales valued in the millions

July 19, 2005 -- Visa USA Inc. and American Express Co. are cutting ties with the payment-processing company that left 40 million credit and debit card accounts vulnerable to hackers in one of the biggest breaches of consumer data

Visa, Amex Cut Ties with CardSystems

Jan 18, 2007Massive Security Breach Reveals Credit Card DataThe TJX Companies, a large retailer that operates more than 2,000 retail stores under brands such as Bob’s Stores, HomeGoods, Marshalls, T.J. Maxx and A.J. Wright, said on Wednesday that it suffered a massive computer breach on a portion of its network that handles credit card, debit card, check and merchandise transactions in the United States and abroad.

CNBC's Easy MoneyBusinessWeek uncovers that the cable channel's own design flaw may be behind the investigation into its million-dollar stock-picking contest

USDA admits data breach, thousands of social security numbers revealedThursday, 17 April 2007 (AXcess News) Washington - The US Department of Agriculture (USDA) admitted that a security breach allowed social security and other personal information of over 63,000 recipients of federal farm loans be made available on a public website in violation of Federal privacy laws.


Holistic Approach to SecurityHolistic Approach to Security

Port blockingFilteringEncryption

UpdatesIIS hardeningACLsCASLoggingLeast privilegeAccount mgmt.

ValidationHashingEncryptionSecrets mgmt.Cookie mgmt.Session mgmt.Error handling

Spoofed packets, etc.

Buffer overflows, illicit paths, etc.

SQL injection, XSS, input tampering, etc.

Network Host Application

Defend the network

Defend the host

Defend the application


Hacking with GoogleHacking with Google

http://www.amazon.com/gp/product/images/1931836361/ref=dp_image_0/102-7668281-7046503?_encoding=UTF8&n=283155&s=books


Security in the Development LifecycleSecurity in the Development Lifecycle

RequirementsRequirementsAssessmentAssessment

DesignDesignCompleteComplete

Test PlansTest PlansCompleteComplete

CodeCodeCompleteComplete

ShipShip PostPostShipShip

Applying SecurityApplying SecurityPatternsPatterns

ExternalExternalReviewReviewDevelopmentDevelopment

TeamTeamTrainingTraining

SecuritySecurityTestingTesting

Secure Programming TechniquesSecure Programming TechniquesSource Code ReviewsSource Code ReviewsStatic Analysis ToolsStatic Analysis ToolsReview Check-InsReview Check-Ins

Penetration TestPenetration TestLearn andLearn andImproveImprove

External ReviewExternal Reviewand/or Testand/or TestThreatThreat

ModelingModeling

Support andSupport andIncident ResponseIncident Response

AssessingAssessingSecuritySecurityRequirementsRequirements

Use of DesignUse of DesignPrinciplesPrinciples

InspectingInspectingPreviousPreviousVulnerabilitiesVulnerabilities


Guiding Design PrinciplesGuiding Design Principles

Secure the weakest link Practice defense in depth Fail securely Follow the principle of least privilege Compartmentalize Keep it simple Remember that hiding secrets is hard Be reluctant to trust


Attack Surface Reduction (ASR)Attack Surface Reduction (ASR)

A system's attack surface is the set of ways in which an attacker can enter and potentially cause damage to the system

The measure of a system's attack surface is an indication of the system's security The larger the attack surface, the more insecure the system


Reducing the Attack SurfaceReducing the Attack Surface

Reduce the amount of running code 80% of your users actually use the functionality? If not, turn it

off

Reduce entry points If you can do the same with less ports, sockets, service entry

points etc., then just do it

Reduce access to entry points by untrusted users Restrict access to network endpoints used by your application

to the local subnet or IP range


Input ValidationInput Validation

All data coming from untrusted sources should be validated before being processed It might be possible to tamper application flow and/or

behaviour with invalid data

What you can trust depends on the application context Users Applications on same host Shared libraries (.so, .dll etc.) OS interfaces Other modules in the same app.


Blacklisting is “Bad”Blacklisting is “Bad”

Endless security issues with PHF (mid 1990’s) Command injection (improper input validation) Fix through blacklisting Command injection, round 2 (in just two days) Fix through blacklisting Command injection, round 2 (in just another day) Fix through whitelisting (Problem solved)

Command injection, SQL injection, LDAP injection etc.


Sample SQL InjectionSample SQL Injection

Sample vulnerable code fragment

When criteria is SECURITY

When criteria is “’; DELETE FROM news--”

$query = “SELECT title FROM newsWHERE body LIKE ‘%” . $criteria . ”%’”;

SELECT title FROM news WHERE body LIKE ‘%SECURITY%’

SELECT title FROM news WHERE body LIKE ‘%’; DELETE FROM news--%’


What would be the Query?What would be the Query?

Select * from users where

username = “_1_” and

password = “_2_”;


Cross-Site Scripting (XSS)Cross-Site Scripting (XSS)/location=<script>document.images[4].src=/location=<script>document.images[4].src="http://www.badsite.com/news.jpg"</script>"http://www.badsite.com/news.jpg"</script>


Web is just a messaging protocolWeb is just a messaging protocol


HTML Form TamperingHTML Form Tampering

<FORM METHOD=POST ACTION="/pb/phonebook.php"><INPUT type="hidden" name="sessionID" value=”ad757gj02m357”><INPUT type="hidden" name=“username" value=”pinguin”><INPUT type="submit" name=“Retrieve Entries"></FORM>

1

<INPUT TYPE=text NAME=phonenumber MAXLENGTH=30>2<INPUT TYPE=“radio” NAME=“agegroup” VALUE=“young”><INPUT TYPE=“radio” NAME=“agegroup” VALUE=“middle”><INPUT TYPE=“radio” NAME=“agegroup” VALUE=“old”>

3

<SELECT NAME=“langs”><OPTION VALUE=PHP>Personal Home Page</OPTION><OPTION VALUE=ASP>Active Server Pages</OPTION></SELECT>

4

Validating Form Data in BrowserValidating Form Data in Browser

Client side validations can be bypassed or tampered<HTML><HEAD><TITLE>Client Side Validation Example</TITLE><SCRIPT LANG="Javascript1.2"></SCRIPT></HEAD><BODY><FORM NAME=myform ONSUBMIT="return checkmail()"><INPUT TYPE=text NAME=email MAZLENGTH=50><INPUT TYPE=submit VALUE=“Submit"></FORM></BODY></HTML>


Error MessagesError Messages

Error messages might reveal sensitive information to a potential attacker Portions of an SQL statement Error message that includes brand/version of database or

directory server Error message for a file that doesn’t open up …

Handle all failure cases that you can foresee, configure the environment to log (and not display) verbose error messages


Filesystem Operations and SecurityFilesystem Operations and Security

Any component that operates on files is of high risk If input validation is broken somehow

Arbitrary files might be read Arbitrary files might be overwritten Arbitrary files might be uploaded & executed

Beware critical symbols for filesystem objects and the OS shell. .. && || > < *

; null (%00)


Easy to Guess Files and DirectoriesEasy to Guess Files and Directories

There are things to discover by just educated guessing /CVS /admin /test README INSTALL backup.zip


Backup FilesBackup Files

Would one of them be left somewhere? mycode.jsp~ mycode.jsp.OLD mycode.jsp.ORIG mycode.jsp.BACK mycode.jsp.BAK


Directory ListingsDirectory Listings

Directory listings should be turned-off for all servers/sites

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