What you will learn
- The business case for penetration testing, supported by current breach data
- How pen tests differ from vulnerability scans, and where each fits
- Compliance drivers, including PCI DSS 4.0 and ISO 27001
- Exactly how to scope, schedule, and resource a program in small steps
- Cost ranges, vendor evaluation criteria, and sample deliverables
- Metrics to prove value to leadership
Why penetration testing matters now
Breaches remain frequent and expensive. IBM’s 2025 report puts the global average breach cost at about 4.44 million dollars, with higher costs in the United States. Multi environment breaches cost even more and take longer to contain. These numbers reflect direct response costs and indirect impact like churn and downtime
Attack patterns also keep shifting. Verizon’s 2025 DBIR analyzed more than twenty two thousand incidents and over twelve thousand confirmed breaches. Stolen credentials dominate basic web app attacks, and vulnerability exploitation increased year over year, which means weaknesses in identity and patching pipelines remain prime targets.
Rapid adoption of AI creates new risk. Studies this year highlight “shadow AI,” where employees use unapproved models and plug ins, and compromises linked to AI supply chains. Organizations without strong AI access controls face higher incident costs. Pen tests that include AI related threat modeling help close these gaps.
Penetration testing addresses these realities by safely simulating attacker behavior against your systems. It validates the true exploitability of findings, quantifies business impact, and provides prioritized remediation steps that your teams can execute within sprint cycles. For many businesses, this is not optional, it is essential to operate with confidence.
Expert note, Dr. Lina Moretti, CISO advisor: “Modern pen testing is less about volume of findings and more about demonstrating credible, end to end attack paths. Boards fund what they can see, so validated paths to sensitive data drive action.”
Definition, pen testing vs. scanning
Penetration testing is a controlled, authorized exercise where security professionals attempt to breach systems to identify and validate exploitable weaknesses, then document impact and fixes.
Vulnerability scanning automatically enumerates known weaknesses and misconfigurations at scale.
When to use scanning
- Continuous hygiene, weekly or monthly
- Patch validation after changes
- Breadth across large inventories
When to use pen testing
- Validate risk with proof of exploitability
- Assess complex business logic in apps and APIs
- Prove compliance, due diligence, or M&A readiness
- Simulate realistic attacker goals and paths
NIST SP 800 115 remains a stable reference for methodology and terms. It outlines planning, discovery, attack, and reporting phases that organizations can adapt to their environment.
Compliance drivers you cannot ignore
Many regulations and standards expect or explicitly require penetration testing.
- PCI DSS 4.0: Requires annual penetration testing and after significant changes, including segmentation validation and industry accepted methodologies. Requirement groupings around 11.4 and related controls make this clear.
- ISO 27001: While the standard does not prescribe a fixed frequency, Annex A controls and risk treatment commonly lead to scheduled penetration tests to validate technical controls.
- Customer and auditor expectations: Enterprise due diligence, vendor risk assessments, and SOC reports frequently ask for recent, independent pen test evidence.
If PCI scope or cardholder data is involved, consider a partner that understands both web app and network layers, and can retest after remediation to close the loop. For a deep dive on web application testing services and what a modern engagement includes, see the Penetration Testing Services overview on DeepStrike.
https://deepstrike.io/services/penetration-testing-services
What a great pen test includes
1. Clear objectives and measurable success
Tie each test to a business outcome. Examples include preventing account takeover, verifying tenant isolation in a multi tenant SaaS, or validating token lifetime and refresh flows in OAuth and mobile.
2. Methodology that maps to NIST SP 800 115
- Planning: scope, rules, risk treatment, safe hours
- Discovery: asset and endpoint mapping, technology fingerprinting
- Attack: exploitation, lateral movement, data access validation
- Reporting: impact narratives, ranked fixes, retest plan
This structure aligns with NIST’s guidance and improves repeatability.
Program design, from zero to mature in 90 days
Phase 1, week 1 to 3, establish the baseline
- Inventory high value assets: PII stores, payment flows, admin portals
- Define risk scenarios: attacker goals, internal and external
- Pick a scoped quick win: one critical web app and associated APIs
- Run a targeted web and API pen test with retest built in
- Remediate top 5 issues, verify with retest and change the defaults
- Phase 2, week 4 to 8, expand and automate
- Add SSO and session management tests across user roles
- Test cloud posture around identity and secrets
- Baseline continuous scanning for drift, connect results to patch SLAs
- Create a quarterly pen test cadence, after major releases or infra changes
- Phase 3, week 9 to 12, prove and scale
- Add segmentation and external perimeter tests
- Include mobile or thick clients if they exist
- Practice incident response with findings based tabletops
- Share risk reduction metrics with leadership
- This crawl then walk approach aligns with PCI DSS expectations on frequency and change driven testing, and it gives engineering a sustainable rhythm.
Cost, time, and team resourcing
- Entry scope web and API pen test: one to two weeks, typically low five figures depending on complexity, auth models, and environments
- Broader scope with external and internal segments: three to six weeks, involves more testers and scheduling
- Ongoing cadence: quarterly for high change apps, annual for low change systems, and always after significant changes per PCI or internal policy
Look for vendors who include free retesting, precise scoping, and artifact delivery that speeds your fixes. If you need a reference service description and sample outputs, review DeepStrike’s Web Application Penetration Testing Services page to align expectations with your team.
Web Application Penetration Testing Services
Metrics that matter to leadership
- Mean time to remediate, high risk
- Attack path reduction, quarterly
- Coverage, critical apps and APIs tested
- Reoffense rate after retest
- Control validation: session management, MFA, secrets, and logging
Tie each metric to a cost lever. Faster remediation saves incident hours. Fewer viable attack paths reduce the chance of a major disruption. IBM and Verizon data can provide benchmarks when you need to quantify risk for the board.
Pen test deliverables, what to expect
- Executive summary: risk themes, business impact
- Validated vulnerabilities: steps, evidence, exploitability, impact
- Affected assets and owners: system mapping and versioning
- Developer guidance: code level fixes, secure defaults, references
- Retest report: verification and closure notes
- Compliance appendix: how findings map to PCI, ISO, or internal policies
Expert note, Amir Rahman, Principal Tester: “A good report reads like a story of how we got from an external IP to sensitive data. Screenshots, logs, and code snippets give engineers everything they need to fix issues fast.”
Common pitfalls, with practical fixes
- Over reliance on scanners. Add manual testing for logic and role abuse.
- Scope too wide, no depth. Start small, add depth, then expand.
- No retesting. Budget retest time during scoping.
- No owner for each fix. Assign finding owners and due dates.
- Skipping change driven tests. Test after significant releases and migrations, which aligns with PCI DSS and common audit expectations
How to evaluate a vendor
- Methodology alignment: NIST SP 800 115 style, PCI 4.0 familiarity
- Team composition: manual testing strength, app, API, cloud, and identity
- Sample reports: ask for a redacted sample with code level guidance
- Retest policy: included at no extra cost
- References: similar industry, similar architecture
- Security of testing: safe handling of data and credentials, logging and destruction policies
Frequently asked questions
How often should we run a pen test?
At least annually and after significant changes. High change applications benefit from a quarterly cadence. PCI DSS 4.0 requires both periodic and change driven testing.
Do we need both scanning and pen testing?
Yes. Scanners give breadth and continuous coverage. Pen tests add depth and validate real exploitability. NIST SP 800 115 outlines how to combine both in a program.
What counts as a significant change?
Major releases, architectural shifts, new payment flows, identity provider migrations, cloud re segmentation, or anything that meaningfully alters attack surface. PCI guidance calls for testing after changes.
Will pen testing cause downtime?
Engagements are planned to avoid disruption. High risk actions are coordinated, with maintenance windows and rollbacks defined in the rules of engagement.
What about ISO 27001 audits?
Pen tests are not a hard coded ISO requirement, yet they are commonly used to validate controls and reduce risk as part of Annex A control implementation.