Technical debt"Shipping first time code is like going into debt. Alittle debt speeds development so long as it ispaid back promptly with a rewrite. The dangeroccurs when the debt is not repaid. Every minutespent on not-quite-right code counts as intereston that debt."
Security debt…• Present in all software• Analogous to development and bugs • security is just a type of bug• Analogous to development and tech debt• The trade off between • fix everything and ship nothing -versus- • fix only the critical -versus- • real world business
Security debt…• You get good…• .. you get a new problem• Too many vulnerabilities!• You focus on just the critical / serious• … the low / medium mountain grows
Security debt – types?• Known – identified, but yet to be addressed• Unknown – latent issues yet to be discovered
Security debt – source?• Selfmy development• Supply chainmy outsourced development• DependencyCOTS component use without formal support
Security debt and SDLs• SDL does not mean 0 debt• SDL means known security debt • with a repayment plan• No SDL means latent security debt • with no repayment plan• SDL means more bugs than resources • quite quickly / in the short to medium term• SDL means accelerated discovery • you get too good
Security debt and SDLs• Why accelerated discovery? • requirements reviews • static code analysis • manual code analysis • automated testing (fuzzing) • increased awareness and knowledge • root cause analysis and variations
Accruing debt based on risk• Financial cost versus • Revenue • Cost of a response incident • Brand impact • Liability• Time cost versus • Resources • Time to market • Financial costs
Accruing debt based on risk• Impact versus • Discovery • Mitigations • Complexity and prerequisite conditions • Access requirements • Marker expectation
Latent debt resilience• Latent debt will always exist • through own activities • through suppliers • through dependencies• The need to feed upstream• The need to build resilient software
Debt Overhang• Stuart Myers paper (1977) ‘Determinants of Corporate Borrowing’• Debt mountain equals death by a thousand cuts• Leading to inability to accrue more security debt• Leading to slower innovation
Non Repayment – Consequence Planning"We may be at the point of diminishing returns bytrying to buy down vulnerability," the generalobserved. Instead, he added, "maybe it’s time toplace more emphasis on coping with theconsequences of a successful attack, and trying todevelop networks that can "self-heal" or "self-limit“the damages inflicted upon them. "
Conclusions• Zero debt is not good business practice• SDLs enable debt discovery and repayment• A pure risk approach allows the mountain to grow• Outsourcing carries risk of larger latent debt• A mature model is to understand and plan payment• … while educating upstream• … while paying down the mountain• … while still using risk
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