Dropbox security glitchCASE STUDY

Lewis ScaifeSYSM 6309 Advanced Requirements Engineering

Summer 2013Professor – Dr. Lawrence Chung

The Problem/Incident• Internal company action compromised system security.• Software patch/update introduced software bug compromising authentication mechanism.•On June 19, 2011 from 1:54pm PT until 5:46pm PT, all users accounts could be accessed using any password.

Impact•Dropbox had 25 million users at the time of the incident.• Loss in confidence that data is secure within Dropbox infrastructure.• Loss of confidence in cloud community as a whole.

Company ResponseHi Dropboxers, Yesterday we made a code update at 1:54pm Pacific time that introduced a bug affecting our authentication mechanism. We discovered this at 5:41pm and a fix was live at 5:46pm. A very small number of users (much less than 1 percent) logged in during that period, some of whom could have logged into an account without the correct password. As a precaution, we ended all logged in sessions.We’re conducting a thorough investigation of related activity to understand whether any accounts were improperly accessed. If we identify any specific instances of unusual activity, we’ll immediately notify the account owner. If you’re concerned about any activity that has occurred in your account, you can contact us at support@dropbox.com.This should never have happened. We are scrutinizing our controls and we will be implementing additional safeguards to prevent this from happening again.-Arash

Process•Were software requirements specified?

•Were quality controls in place during software development?

•Did Dropbox test software patch before deploying it within their production environment.?

Regression Testing•Functionality of existing code should not change when new code is inserted within the program.

•Attempts to find bugs introduced by small changes/updates in a program.

•Test case selection and prioritization.

Goals for Case Study•Develop measures to decrease the probability of a software bug causing authentication vulnerabilities.

•Research testing and validation tools which can be used to verify functionality of code prior to release.

• Present findings.

Deliverable• No data was obtained that identified the segment of code

that caused the error.

• The security glitch was most likely caused by access control or authentication system failures.

• Authentication bypass• Access control check

• Processes and Tools.

ScenarioI need the new

software functionality implemented and

placed in production today!!

Sure thing! I am almost finished. The code update will be

ready today.CODE

#include <time.h>Int = 100a=bcIf a=100do (a=b+c)

Production Server

Boss

Programmer/s

ScenarioHave you all been to

the new Dropbox website? Yes. They made a new

code change. The site looks great!!

I will check it out after lunch.

Scenario

Production Server

www.dropbox.com

Scenario

Production Server

Web User: User X Password: *****

Scenario

Web User: User X Password: *****

Wait! I successfully

logged in with the incorrect

password

Scenario

I want answer!

Customers

DropboxCustomer Service

Scenario

CODE

#include <time.h>Int = 100a=bcIf a=100do (a=b+c)

Fix it NOW!

Right away!

Production Server

Boss

Programmer/s

Corrected Program

Scenario

Web User: User X Password: ***** I am happy

they fixed the authentication issue. I feel

my information is secure again

I will never use

Dropbox again !!!

Solution• Process

• ITIL• Security Audit

Solution• Tools

•Nemesis

•Used to mitigate Authentication and Access Control Vulnerabilities in Web Applications.

Nemesis• How it works….• Shadow authentication system that tracks flow of user

credentials through application’s runtime.

• Dynamic Information Flow Tracking (DIFT).• Relies on some developer input.• Does not rely on correctness of existing code.• Agnostic.• Tracks two bits:

⁻ Credentials⁻ User Input

Nemesis• Provides a system of checks and balances.• It interfaces with the web application authentication systems and verifies all access control and user inputs are satisfied before granting access.

ScenarioI need the new

software functionality implemented and

placed in production today!!

Sure thing! I am almost finished. The code update will be

ready today.

CODE

#include <time.h>Int = 100a=bcIf a=100do (a=b+c)

Boss

Programmer/s

Development Server

Security Audit

PASSFAIL

Production Server

Nemesis

ScenarioHave you all been to

the new Dropbox website? Yes. They made a new

code change. The site looks great!!

I will check it out after lunch.

Scenario

Production Server

www.dropbox.com

Scenario

Production Server

Web User: User X Password: *****

Nemesis

Scenario

Dropbox is the best !!!

Questions

?

References• M. Dalton, C. Kozyrakis, and N. Zeldovich. Nemesis:

Preventing Authentication and Access Control Vulnerabilities in Web Applications. In Proceedings of the USENIX Security Symposium, 2009.