Edge Computing Attack

Edge Computing Attack

Supplementary Files:

• payloads.md — Attack payloads organized by edge platform: Cloudflare Workers (V8 isolate escape, KV abuse), Fastly Compute@Edge (WASM sandbox), AWS Lambda@Edge / CloudFront Functions, Akamai EdgeWorkers, Vercel Edge Functions, Deno Deploy
• test-cases.md — 18 structured test cases covering reconnaissance, edge script injection, KV/Kvstore abuse, isolate escape attempts, request smuggling, and origin WAF bypass
• guides/edge-computing-attack-playbook.md — End-to-end playbook with engagement scoping, lab setup (local Wrangler, Fastly CLI, SAM Local), attack workflows, and blue-team detection engineering
• guides/real-world-incident-case-studies.md — Eight case studies including the 2024 Cloudflare Workers KV incident, AWS Lambda@Edge CVE-2023-XX pattern, Fastly WASM breakouts, and Deno Deploy SSRF waves

Summary

This skill targets edge computing — where code runs in geographically-distributed nodes close to end users, typically in V8 isolates (Cloudflare Workers), WASM sandboxes (Fastly Compute@Edge), or restricted JavaScript engines (AWS CloudFront Functions, Lambda@Edge). The attack surface differs from origin-side attacks: edge platforms handle TLS termination, request routing, and caching, and their security model assumes a trusted-but-curious operator with strong tenant isolation.

Tools: wrangler, fastly-cli, sam-cli (SAM Local), gcloud edge, akamai-cli, vercel-cli, deno, vitesspa, chromium-headless, burp suite, postman, curl, jq

Domain: edge-computing

MITRE ATT&CK: T1190 Exploit Public-Facing Application · T1552.007 Container and Cloud Instance Credentials API · T1059 Command and Scripting Interpreter

Description

Attacks against edge computing platforms — Cloudflare Workers (V8 isolate), Fastly Compute@Edge (WASM/Wasmtime), AWS Lambda@Edge and CloudFront Functions, Akamai EdgeWorkers, Vercel Edge Functions, and Deno Deploy.

Edge platforms share common architecture: code runs in isolates (V8) or sandboxes (WASM), often co-located with hundreds of other tenants on the same physical machine. The threat model assumes:

• Operator (CSP) is trusted to enforce isolation
• Other tenants are NOT trusted (cross-tenant attacks possible)
• Origin servers may be inaccessible directly (all traffic flows through edge)
• Edge scripts have access to KV stores, secrets, and request/response bodies

This skill is distinct from:

• cloud-security — which targets CSP control planes (IAM, EC2, S3) broadly
• container-security — which targets Linux namespaces and cgroups
• web-ssrf — which targets origin-side SSRF (edge-side SSRF has different rules)
• api-security — which targets REST/GraphQL endpoints, not edge routing

Where container-security asks "can I escape this container?", edge-computing-attack asks "given that my Worker shares a V8 isolate pool with 10,000 other tenants, how do I leak their secrets via shared state, KV race conditions, or isolate escape?"

Coverage includes:

• Cloudflare Workers: V8 isolate escape attempts, KV race conditions, Durable Objects abuse, Workers AI prompt injection, R2 storage abuse, Pages Functions injection
• Fastly Compute@Edge: WASM sandbox bypass, WASI host-call misuse, secret store leakage, edge KV abuse
• AWS Lambda@Edge / CloudFront Functions: token theft from env, origin WAF bypass via edge-managed headers, CloudFront function code injection
• Akamai EdgeWorkers: bypass of edge-based ARL parsing, Property Manager manipulation
• Vercel Edge Functions / Edge Config: env var leakage, Edge Config race conditions
• Deno Deploy: V8 isolate escape, KV store race conditions
• Universal edge patterns: cache poisoning, request smuggling (CL.TE / TE.CL via edge), TLS SNI manipulation, host header injection at edge, geographic DNS hijack prep

Use Cases

• Cloudflare Workers KV race condition — concurrent reads/writes to same key to leak tenant data
• Cloudflare Workers V8 isolate escape — exploit V8 bugs (or Workers-specific quirks) to break isolation
• Cloudflare Durable Objects abuse — single-threaded object state to leak cross-tenant data
• Cloudflare Workers AI prompt injection — indirect prompt injection via Worker to leak secrets
• Fastly Compute@Edge WASM escape — exploit Wasmtime bug to escape sandbox
• Fastly Secret Store leakage — read secrets via misconfigured token
• AWS Lambda@Edge env var leakage — exploit logging side channel
• AWS CloudFront Function code injection — inject JS into edge function
• Akamai EdgeWorkers bypass — bypass ARL-based access control
• Vercel Edge Config race — concurrent reads to expose other tenant's config
• Deno Deploy KV race — concurrent KV operations to leak data
• Origin WAF bypass via edge header manipulation — set X-Forwarded-For to bypass IP-based rules
• Cache poisoning via edge — poison edge cache to serve malicious content to other users
• Request smuggling at edge — CL.TE via edge HTTP/2 → origin HTTP/1.1 boundary

Differentiation from Adjacent Skills

Core Tools

Cloudflare Workers

• wrangler — official Workers CLI; deploy, dev, KV, R2
• miniflare — local Workers emulator for testing
• cloudflare-api-cli — direct REST API access
• workers-typescript-template — boilerplate for TS Workers

Fastly Compute@Edge

• fastly-cli — official Compute@Edge CLI
• wasmtime — local WASM runtime for testing
• fastly-compute-starter — Rust/JS starter kits

AWS Lambda@Edge / CloudFront Functions

• aws-cli — Lambda and CloudFront API
• sam-cli — local SAM emulation for Lambda testing
• cloudfront-testing-tools — request-response replay

Akamai EdgeWorkers

• akamai-cli with edgeworkers plugin
• akamai-sandbox — local EdgeWorkers emulator

Vercel Edge

• vercel-cli — Vercel deployment CLI
• next.js edge runtime testing

Deno Deploy

• deno — Deno runtime
• deployctl — Deno Deploy CLI

Universal

• curl — edge protocol testing
• Burp Suite — request/response tampering
• Wireshark — packet capture (limited use; most edge is TLS)
• vitesspa — Vite + SPA testing harness
• chromium-headless — end-to-end browser testing

Methodology

Phase 1 — Reconnaissance

• Identify edge platform via HTTP headers (Server: cloudflare, X-Fastly, X-Amz-Cf-Pop, X-Akamai-Transformed, X-Vercel-*)
• Identify edge functions in use (timing analysis, behavior fingerprinting)
• Map edge KV store usage (timing, error patterns)
• Identify origin WAF patterns (security headers)
• Map request routing (geo DNS, edge POPs)

Phase 2 — Edge Script Discovery

• Inspect client-side JS for cf: / cdn-cgi/ indicators
• Use Wrangler dev mode for local Cloudflare Workers inspection (if authorized)
• Analyze edge function behavior via timing and error patterns
• Identify Worker bundling via DevTools / source maps (often enabled)

Phase 3 — Tenant Isolation Testing

• Deploy own Worker on same platform
• Test for shared isolate patterns (timing, leak)
• Test KV store race conditions
• Test Durable Object cross-tenant access
• Test Deno Deploy KV cross-tenant

Phase 4 — Edge Script Injection

• Inject malicious edge script (if edge function has injection vuln)
• Test edge function input validation (headers, query, body)
• Test edge function source map leakage

Phase 5 — Cache and Routing Attacks

• Cache poisoning via edge header manipulation
• Request smuggling at HTTP version boundary
• Geographic DNS hijack preparation
• Host header injection at edge

Phase 6 — Origin WAF Bypass

• Test edge header manipulation (X-Forwarded-For, X-Real-IP)
• Test edge-based request rewriting
• Test edge script that adds headers trusted by origin
• Test CloudFront signed URL bypass

Phase 7 — Secret and Data Exfiltration

• Edge KV store exfiltration via race condition
• Edge logs containing secrets (Worker logs often include env vars)
• Workers AI prompt injection for secret leak
• Durable Objects state exfiltration

Phase 8 — Persistence

• Persistent edge Worker via compromised deploy token
• Persistent cache poisoning
• Persistent KV store pollution
• Persistent DNS hijack prep

Defense Perspective

Core Principles

1. Edge is privileged — edge scripts see all traffic including TLS-terminated plaintext
2. Tenant isolation is critical — KV, Durable Objects, Edge Config must enforce hard isolation
3. Cache is shared state — cache poisoning affects other tenants
4. Origin must NOT trust edge headers — X-Forwarded-For etc. can be set by attacker
5. Logs are sensitive — edge logs often contain secrets in headers/body

Hardening Checklist

• Validate X-Forwarded-* headers at origin (don't trust blindly)
• Rotate edge deployment tokens quarterly
• Audit edge function code for injection
• Use Cloudflare's API tokens (not Global API Key) for CI
• Restrict Worker secrets to specific Workers via bindings
• Enable Fastly Compute@Edge secret store ACLs
• Use signed URLs for CloudFront protected content
• Audit Vercel Edge Config access patterns
• Apply Deno Deploy KV access controls
• Monitor edge function logs for secret patterns

Detection Engineering

• Edge function log anomaly detection (unexpected env var reads)
• KV store race condition detection (concurrent operations)
• Cache hit ratio anomaly (potential poisoning)
• Edge function cold start anomaly (potential injection)
• Edge-to-origin header consistency checks

Practical Steps

Cloudflare Workers Recon

# Identify Cloudflare
curl -sI https://target/ | grep -i server
# Server: cloudflare

# Identify edge POP
curl -sI https://target/ | grep -i cf-ray
# CF-RAY: 85abc123.def-LAX (LAX = Los Angeles POP)

# Detect Worker
curl -s https://target/cdn-cgi/trace
# Identifies colo, request source, etc.

# Worker source map leak (often enabled)
curl -s https://target/script.js.map

Cloudflare Workers KV Race

// Deploy own Worker with KV binding
// Race condition: read-write-read pattern

// Worker code:
addEventListener('fetch', event => {
  event.respondWith(handleRequest(event.request));
});

async function handleRequest(request) {
  const key = 'shared_key';

  // Read value
  const initial = await KV.get(key);

  // Write attacker value
  await KV.put(key, 'attacker_value');

  // Read again quickly — may catch another tenant's write
  const after = await KV.get(key);

  return new Response(JSON.stringify({ initial, after }));
}

Fastly Compute@Edge Recon

# Identify Fastly
curl -sI https://target/ | grep -i "X-Fastly"
# X-Fastly: hit
# X-Served-By: cache-lax1234-LAX

# Detect Compute@Edge usage
curl -sI https://target/ | grep -i server
# Server: Fastly Compute

# WASM source map leak
curl -s https://target/.well-known/fastly/source

AWS Lambda@Edge Recon

# Identify CloudFront
curl -sI https://target/ | grep -i "X-Amz-Cf"
# X-Amz-Cf-Pop: LAX1-C1
# X-Amz-Cf-Id: ...

# Lambda@Edge logs in CloudWatch (us-east-1)
aws logs describe-log-groups \
  --region us-east-1 \
  --log-group-name-prefix "/aws/lambda/"

# CloudFront Function source
aws cloudfront list-functions
aws cloudfront describe-function --name REPLACE_WITH_YOUR_FUNCTION

Vercel Edge Recon

# Identify Vercel
curl -sI https://target/ | grep -i "X-Vercel"
# X-Vercel-Cache: HIT
# X-Vercel-Id: vercel-sfo1:abc-def

# Edge Config endpoint
curl -s https://target/_vercel/edge-config/_default

Detection Methods

CDN / Edge Function Logs

• Cloudflare Workers abuse: Anomalous Worker invocations; outbound fetch to attacker domains.
• AWS Lambda@Edge anomalies: Function duration spikes; cross-region data egress from edge.
• Origin IP discovery: Direct origin access bypassing CDN (signature: requests to origin IP from internet).

SIEM Detection Rules

• Splunk SPL: index=cdn sourcetype=cloudflare:workers | stats count by script | sort -count | head 10
• Cloudflare Analytics: Native bot/security analytics.
• AWS CloudTrail: Lambda@Edge invocation logs; alert on cross-region data egress.

Defense Evasion Techniques

CDN Bypass

• Direct origin access: Find origin IP via DNS history, leak in HTTP headers, SSL cert; bypass CDN/WAF.
• Cache poisoning: Poison cached response; affect all users of cached resource.
• Cache deception: Trick CDN into caching dynamic content with sensitive data.

Edge Function Exploitation

• Worker script injection: Inject code into Worker via compromised account or supply chain.
• Lambda@Edge privilege abuse: Use Lambda@Edge for global execution; harder to attribute.
• Origin IP rotation: Use direct IP for exfil; CDN sees only legitimate traffic.

Cross-References

• skills/cloud-security/SKILL.md — broader CSP control plane attacks
• skills/container-security/SKILL.md — Linux container escapes
• skills/web-ssrf/SKILL.md — origin-side SSRF (compare to edge-side)
• skills/dns-attacks/SKILL.md — DNS attacks relevant to edge routing
• skills/api-security/SKILL.md — API gateway attacks
• skills/persistence-attacks/SKILL.md — edge-side persistence patterns
• skills/cdn-cache-attack/SKILL.md — CDN-specific cache attacks

References

• Cloudflare — Workers Security Model (2024)
• Fastly — Compute@Edge Security Documentation (2024)
• AWS — Lambda@Edge Security Best Practices (2024)
• Akamai — EdgeWorkers Security Guide (2024)
• Vercel — Edge Functions and Edge Config Documentation (2024)
• Deno — Deno Deploy Threat Model (2024)
• Bishop Fox — Edge Computing Attack Vectors (2024 whitepaper)
• Black Hat USA — Cross-Tenant Attacks in Edge Platforms (2024)
• MITRE ATT&CK — T1190 Exploit Public-Facing Application, T1552.007 Container and Cloud Instance Credentials API