Serverless and AWS Lambda Security Review
Every function carries its own IAM role, and roles get copied. The pattern we find is a dozen functions sharing one over-permissioned role because it was easier than writing twelve, so compromising the least important one reaches everything. CREST-certified testers, fixed price from £3,350, scoped in 24 hours.
- Unlimited retesting
- No rescheduling or cancellation fees
- Fixed quote within 24 hours
“I would highly recommend EJN Labs to any organisation seeking reliable, detailed, and well-managed penetration testing services, particularly for government or enterprise-level projects.”
Imran SaghirProject Lead, SquareOne“There wasn’t another company we could find that could deliver what we needed in the timeframe we needed. The client loved it, and we got instant ROI from the engagement.”
Dan WilcocksonCo-Founder, CelloriThere is no server to harden, which removes a class of problems and concentrates what remains into identity and event handling. A function’s blast radius is exactly what its execution role permits, so the review is largely an IAM exercise with code attached.
Why serverless moves the risk into IAM
Event source trust is the part teams most often miss. A function triggered by S3, SQS, EventBridge or an API Gateway will happily process an event that did not come from where it expects, unless something checks. Functions that assume the event is trustworthy tend to treat its contents as trustworthy too.
Then it is the ordinary application questions in an unusual shape: injection through event payloads, secrets in environment variables visible to anyone who can read the function configuration, and dependencies pulled at build time from a public registry.
ISO 27001, SOC 2, PCI DSS and Cyber Essentials Plus audits accept manual penetration test evidence. Scan-only evidence is generally insufficient.
ROLES, EVENTS + DEPENDENCIES
What we actually pen test on a serverless estate
Manual pen testing across execution role scope, event source trust, environment variables, API Gateway authorisers, dependency supply chain and function isolation.
Execution role scope
Every function’s IAM role enumerated and tested for what it actually reaches, roles shared across functions, wildcard resource and action grants, and whether a compromised function can escalate through iam or sts actions.
Event source trust and validation
Whether the function validates the origin and shape of its event, injection through event payloads, replay of captured events, and whether an attacker can place a message on the triggering queue or topic.
Environment variables and secrets
Secrets in environment variables versus a secrets manager, encryption at rest, who can read the function configuration, and whether secrets appear in logs or error responses.
API Gateway and authorisers
Custom and JWT authoriser logic, authoriser caching behaviour, whether a route is exposed without an authoriser, resource policy configuration, and throttling on expensive functions.
Dependencies and layers
Third-party packages and Lambda layers enumerated for known vulnerabilities, whether dependencies are pinned, and what a compromised package would obtain from the execution environment.
Function isolation and state
Warm start state leakage between invocations, temporary storage reuse, whether one tenant’s data can persist into another’s invocation, and concurrency and cost abuse.
METHODOLOGY
Serverless and AWS Lambda Security Review: From Scope to Attestation
CREST-aligned methodology built on OWASP Web Security Testing Guide, OWASP ASVS, NIST SP 800-115, and PTES. Each finding maps to all four standards plus your specific compliance regime.
Reconnaissance
Application mapping, technology fingerprinting, content discovery, parameter enumeration, authentication-flow analysis, role-matrix construction.
Vulnerability Assessment
Authenticated and unauthenticated automated scanning across every user role, plus targeted manual checks for known weakness patterns.
Manual Exploitation
Hands-on testing by a CREST-certified pentester. Business-logic exploitation, chained vulnerabilities, privilege escalation, impact validation.
Reporting + Retest
Executive summary, technical report with CVSS scores and reproduction steps, walkthrough call, free retest after remediation, attestation letter.
CREDENTIALS
Verified Accreditations Auditors Accept
Every credential below is independently verifiable. UK procurement teams, FCA supervisors, ISO 27001 / SOC 2 auditors, and cyber insurance underwriters all recognise these standards.
GET YOUR QUOTE
Get a CREST serverless pen test quote in 24 hours
A fixed-price quote back in one business day, from a named CREST assessor. No sales pipeline, no chasing.
- CREST and IASME accredited. Testing your auditors and clients already recognise.
- Fast-track testing within 24 hours where required. Free retest of every fix included.
- Live findings via your client portal, not a four-week PDF.
- Fixed price from £3,500 for a single-role, single-app scope, agreed up front. Most engagements run £5,000 and up. No day-rate surprises.
Dan WilcocksonCo-Founder, CelloriUnder NDA Further named references available on a scoping call.
- We reply within one business day with a fixed-price quote from a named CREST assessor.
- You approve the scope and we book a start date, usually within 24 hours.
- Live findings land in your client portal as we test, with a free retest of every fix.
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COMPLIANCE READY
Reports Mapped to Every Framework
Findings are explicitly tagged to the relevant control reference. Your audit team submits the report directly without translation work.
ISO 27001:2022
Annex A.8.8 management of technical vulnerabilities plus A.5.15-5.18 and A.8.2-8.5 access control validation.
SOC 2 Type I & II
CC6 logical access, CC7 system operations, CC8 change management evidence.
PCI DSS
Requirement 11.4 application penetration testing across cardholder data environments, including ecommerce penetration testing for online retail platforms.
FCA SYSC
SYSC 4.1.1R, 6.1.1R, 13 mapped to each finding for FCA-regulated firms.
UK GDPR
Article 32 effectiveness testing, customer-data security controls, ICO-acceptable evidence.
Cyber Essentials Plus
Direct certification through our IASME body status, single-vendor delivery.
PRICING
Transparent Serverless and AWS Lambda Security Review Pricing
Pricing depends on app complexity, user-role count, business-logic depth, and integration surface. The day count flexes; the included deliverables stay the same across all engagements.
3 to 4 testing days
Single user role, basic CRUD application, marketing website with auth. Around 5 working days from kickoff to report.
Get a fixed quote4 to 6 testing days
Multi-role SaaS, business application with payment integration. Around 8 to 12 working days from kickoff to report.
Get a fixed quote6 to 8 testing days
Multi-tenant platform, complex authorisation matrix, integration-heavy applications. Around 15 to 20 working days from kickoff to report.
Get a fixed quotePart of Technologies We Pen Test. These are examples of the stacks we publish pages for, not a complete list. If yours is not here we still test it. Related pages:
BY SECTOR
Serverless and AWS Lambda Security Review for Your Sector
Sector-specialist scoping for UK businesses with sector-specific compliance regimes and threat models.
Fintech & FCA-Regulated
FCA SYSC, Open Banking FAPI 1.0, PSD2 SCA, payment-flow scrutiny, KYC/AML testing.
Fintech sector pageSaaS Companies
SOC 2 Type I & II evidence, multi-tenant boundaries, role escalation, customer-tenant isolation.
SaaS sector pageLaw Firms
SRA Cyber Standard, privileged data, conveyancing fraud defence, partner-tier procurement.
Law firm sector pageHealthcare
NHS DTAC, DSP Toolkit v6, UK GDPR Article 32, EHR systems, telehealth platforms.
Healthcare sector pageInsurance
FCA / PRA Operational Resilience, cyber underwriting, claims data, broker portals.
Insurance sector pagePublic Sector
CCS / G-Cloud framework, NCSC-aligned, citizen-facing services, PSN-compliance scrutiny.
Public sector pageWHY EJN LABS
What You Get From Serverless and AWS Lambda Security Review
Six concrete differentiators competitors don’t all match.
CREST-Certified Testers, Verifiable
Every test by a CREST-certified pen tester (CRT, CCT APP, CCT INF where applicable). Verify our company status at crest-approved.org.
24-Hour Startup, Where Required
From signed scope to active testing in a single business day for incident response, audit deadlines, or regulator-driven timelines.
Live Findings, Not 4-Week PDFs
Critical issues reported during testing through your client portal. Your team remediates while testing continues.
Audit-Ready Reports
Executive summary plus full technical report with CVSS scores and explicit framework mappings (ISO 27001, SOC 2, PCI DSS, FCA SYSC).
Free Retests, Standard
Verify remediation of every finding before close-out. Letter of attestation for audit submission included. Most competitors charge £1,500-£3,000 per retest.
UK-Based CREST Testers
Every engagement performed by vetted, UK-based CREST-certified testers, matched to your needs, security clearance, and compliance scope.
FAQ
Frequently Asked
Do you cover Azure Functions as well as Lambda?
Yes. The platform differs but the questions do not: managed identity scope instead of IAM roles, binding trust instead of event source trust, application settings instead of environment variables. We pen test whichever you run.
Do you need AWS access?
Read-only access to the function configuration and IAM policies makes this substantially better, because role scope is where the severity is. Black box testing through the API finds application flaws but misses the escalation paths.
What about Step Functions and orchestration?
In scope where you use them. State machine definitions can carry authorisation logic and pass data between functions, and whether an input can steer the machine down an unintended path is worth testing.
Is this the same as your AWS cloud security review?
Related but narrower. The AWS review covers the account: identity, network, logging, storage. This one focuses on the serverless application and the roles it runs under. Clients with a large serverless estate often want both.
What do we receive?
A report mapped to ISO 27001, SOC 2 and the AWS Foundational Security Best Practices where relevant, a developer write-up with reproduction steps, and unlimited free retesting.
20+ CREST-accredited testing services in one place
Web, mobile, API, cloud, AI, infrastructure, red team. Pick the test that fits your environment.
Get a fixed price for your serverless estate
Tell us roughly how many functions are in scope, which event sources trigger them and whether API Gateway is in play. Fixed-price quote within one business day.
