Rethinking Password Strategies for the 21st Century

Rethinking Password StrategiesRavi SandhuChief Scientistsandhu@nsdsecurity.com703 283 3484

Outline • Security doctrine for the 21st century • Password vulnerabilities and countermeasures • Available technologies

Secure doctrine for the 21st century • Good enough security • Absolute security is not possible • Too much security is counterproductive • Too little security is not acceptable • The goal is to find the sweet spot • Security dollars must work smarter and harder • Security threats are growing • Security budgets are flat and expertise is shrinking • Need more bang for the buck • Prevent catastrophic failure and tolerate sporadic isolated failures • Focus on preventing catastrophic failure • Tolerate sporadic isolated failures

XML, disappearing boundaries, insider theft Online web sites, IDS, worms, insider theft Info Web sites, firewalls, email-viruses, insider theft Illegal modems, floppy-viruses, insider theft The threat environment is getting worse RISK Claim: The potential threat has gone up hundredfold. 1990 1995 2000 2005

Resources and expertise are not growing Skilled resources to address the problems Dollars devoted to problem 1990 1995 2000 2005

Work smarter and harder • Starting point: • Risks went up 100 fold • Security dollars went up a little • Skilled resources went down • So what could happen? • Option: Your security budget goes up enormously • Reality: Security budget stays flat as % of IT budget. The security dollars have to work smarter and harder!

Some thoughts on “smarter”... • Proposition: We waste dollars on non/small problems (the 20/80 rule of security!) • Example: Unnecessary encryption (40 bit vs. 128 bit SSL) • Explanation: • Security has many roots in the cold war era. The communication link was the problem. In our world the end points are a MUCH bigger problem. So why do we waste so many dollars encrypting links unlikely to be attacked? Challenge spending on non-problems

Some thoughts on “smarter”... • Proposition: We are vulnerable to peer pressure. Sometimes our peers are just wrong. • Example: Bank B has to deploy technology/policy X because Bank A did so. And then Bank C, Bank D... Soon we’ve spent scarce dollars on technology/policy of doubtful value. (e.g. password aging) • Explanation: It’s hard to buck a so-called ‘best practice’ in our business, even if the evidence is lacking. Challenge best practices

Some thoughts on “smarter”... • Proposition: the vendor crypto-techno-geeks lead us by the nose. • Example: The entire PKI fiasco. How much did we spend? What value have we seen? Who told the crypto-geeks that they decide what sort of digital signatures are legal? • Explanation: Security is an obscure science where you are trying to prove the negative. Its hard to question the crypto-experts in their Ivory Towers. Challenge the geeks

Some thoughts on “smarter”... • Proposition: Vendor business models drive our infrastructure, as opposed to our needs. • Example: Why do SSL certificates expire annually causing us outages? Who determined that a technology company can better manage a “certificate authority infrastructure” than a bank that secures tens of billions of dollars? • Explanation: FUD (Fear-Uncertainty-Doubt) Challenge vendor business models

Some thoughts on “harder”... • Proposition: Security products must address your “lack of skilled resources” issue. • Example: Many products need “experts” to set up and run them. • Explanation: Most products are designed by the “experts” for the “experts”. They do not realize that most products are run by “non-experts” with little time to get trained on everything. Ask: Can a reasonably competent systems/network person with little security experience run the product?

Some thoughts on “harder”... • Proposition: Security products must be “defensive” • Example: Many security products work great as long as those operating them “walk on water and don’t get their feet wet”. • Explanation: Designed by security geeks who’ve never lived in a real operational world. Ask: Can an average person having a real bad day, be woken at 2AM to fix an issue without opening up a major hole inadvertently?

Some thoughts on “harder”... • Proposition: Security products must address fundamental problems, before the esoteric. • Example: Weak passwords are a major critical problem. Why spend money on esoteric new problems before this is fixed? • Explanation: The fundamental problems are often not “sexy”. Ask: “Before securing the attic window, we should get a better lock on the front door!”

Some thoughts on “harder”... • Proposition: To get more from your security dollars, a security product must solve multiple problems. • Example: One product for passwords, one for PKI, one for 2-factor, one for signatures... (and that’s for the Internet, lets get even more for wireless...) • Explanation: Vendors address niches. Your business sees the big picture. Ask: Can I reuse the product, for multiple functions across multiple channels?

A Common Misperception • Fact: Password based systems are often vulnerable to attacks • Myth: Passwords are inherently insecure. • Fact: It is completely possible to design a sufficiently secure password system. • Fact: A sufficiently secure password system must use some form of PKI under the covers • This is a mathematical theorem proved in 1998 Designing sufficiently secure password-based systems is non-trivial but it is possible by proper use of PKI under the covers.

Another Common Misperception • Fact: Users hate current password systems that require • too many passwords and • force too many changes • Myth: Users inherently hate passwords. • Fact: It is completely possible to design a user friendly password system with PKI beneath the covers Designing user-friendly and sufficiently secure password-based systems is non-trivial but it is possible by proper use of PKI under the covers.

Yet Another Common Misperception • Myth: Security is increased by forcing users to change their passwords frequently • Fact: There is no empirical evidence to show this and much anecdotal evidence to show the opposite • Changing passwords too frequently will degrade security because of user reaction A strong password-based system should not force frequent password changes

Password Vulnerabilities and Countermeasures • End-user Vulnerabilities • User education and awareness • Technology can help mitigate some (but not all) of these • Sniffing Attacks • Everything on the wire should be encrypted • Server Spoofing Attacks • Need server authentication • Guessing Attacks: online • Prevented by throttling • Guessing Attacks: offline (Dictionary attacks) • Prevented by PKI encryption on the wire and hardened password server on the backend

End-user Vulnerabilities • Poor password selection • Users choose easy-to-guess passwords • Countermeasure: enforce complexity rules • Passwords written down by users • Infrequently used passwords are often written down • Countermeasure: reduce number of passwords a user needs to remember • Password shoulder surfing • Password exposed to observant bystander • Countermeasure: user awareness • Password reuse across multiple servers • Password becomes vulnerable at weak servers • Countermeasure: user awareness

End-user Vulnerabilities • Password sharing • Users will share passwords with others only if there is no personal risk • Countermeasure: personal risk must be injected into the system (perhaps by policy and procedure) • Password reset costs • Users forget passwords • Countermeasure: automate password resets BUT be careful not to reduce security too much • Undetected theft • Users are not aware if their passwords are compromised • Countermeasure: detection technology and feedback to the user

Sniffing attacks • Sniffing on the wire is easily prevented by widely deployed technologies such as SSL and IPSEC • No excuse for letting this happen anymore • Sniffing on the desktop by malicious code • Password exposure is limited to a single user • Users need to be free of viruses, worms and Trojan horses for all kinds of reasons • Windows 2000, Windows XP allow tighter control of the desktop by the organization • Ultimately we need stronger platforms that reduce the risk of malicious code

Server-spoofing attacks • To prevent server-spoofing we need server authentication and user awareness • SSL with server-side certificates is a “good enough” and widely deployed solution for this problem • In future we can move to solutions where the password is never communicated to the server • SSL enhanced with password-based client-side certificates is the most promising technology • Need a footprint on the desktop

Guessing Attacks: online • Attacker tries various passwords until he succeeds • Slow down (throttle) the rate at which an attacker can try different guesses • Many strategies are used in practice • 3 strikes and lock the account for password reset • 3 strikes and lock the account for some time • Slowdown each successive guess • Aggressive strategies can lead to denial of service to legitimate users • Loss is limited to small number of passwords

Guessing Attacks: offline aka Dictionary Attack • Attacker obtains “encrypted password” • Attacker tries passwords from a “dictionary” of commonly used passwords and compares with encrypted password • Encrypted password is often “salted” to make this harder • Various studies have shown that 25% to 50% of passwords fall to this attack • This is catastrophic failure • In the past these attacks would take months, with current processor speeds they take hours or days or even less • We are at the point where exhaustive search is feasible so even a dictionary is not needed This is the single biggest vulnerability in most existing password systems and it leads to catastrophic failure

Guessing Attacks: offline aka Dictionary Attack • How to prevent: old approach • Force user to select passwords that withstand dictionary attack • Record shows that this is easier said than done • Trend is that exhaustive search on entire space of human-memorizable passwords is feasible • Password aging to force a change every 30 days or so • Would need to age much faster than 30 days to have any effect on feasibility of attack • “Hide” password files (e.g. shadow files) • Old solution dating to when users had access to ‘system’; current end users usually don’t have access to ‘system’. • Meaningless against hackers and “admin account” compromise • Harden password system OS • Very hard to maintain in hardened manner. • “admin accounts” tend to have carte-blanche access. • Too many insider accounts.

Guessing Attacks: offline aka Dictionary Attack • How to prevent: modern approach • Make password system OS very hard to penetrate. • Use least privilege based partitioning to sharply minimize or eliminate “insider account” attacks. • Use PKI technology to eliminate traditional encrypted password file • Make it non-invasive to end-user (zero client footprint, pure back-end solution). • Make it very easy to integrate with existing systems (e.g. IBM WebSeal, Netegrity, LDAP, Active Directory, etc.)

Secure Identity ApplianceTM Support multiple security levels on a single infrastructure Two-factor PKI Password plus USB token or variant Roaming PKI Password Usability PKI Security Zero Footprint Hardened Password No change for users No change for issuer No password file (PKI hardened) Weak Password Systems, Catastrophic Dictionary attacks

2-Key RSA vs. 3-Key RSA: Hardened Passwords 2-Key RSA Keys: • Alice Public = e • Alice Private = d • Alice Cert = C Challenge/Response: • Challenge sent • Response signed with d • Verified with e and C • Observation: Guessing d from e is extremely difficult. 3-Key RSA Keys: • Alice Public = e • Alice Private = d • Alice has D1=PKCS5(password) • Appliance has D2 • Alice Cert = C Challenge/Response: • Challenge sent • Response signed with D1 • Verified with D2, e and C • Observation: Guessing D1 from D2 is extremely difficult.

3-Key RSA Key 1: Derived from Password Key 2: Verification/Co-Signing Key on Appliance Key 3: Traditional Verification Public Key PKI hardened passwords Systems Partition Security Admin Partition User Admin Partition User Private Data Partition Indepe-pendent Audit Controls Compartmentalized System Hardened Operating System Redundant very high availability architecture Powerful monitoring ability (SNMP based) Appliance Architecture SIA Solution – How it works

Rethinking Password Strategies for the 21st Century