FireProx: How AWS API Gateway Became an Accidental IP Rotation Service

Hook

Every request through AWS API Gateway comes from a different IP address—a side effect of distributed infrastructure that security researchers turned into a feature. FireProx automates this quirk into a command-line tool for on-demand IP rotation.

Context

Traditional IP rotation is expensive and complex. Security professionals conducting authorized penetration testing or web scraping face a common challenge: target systems rate-limit or block requests based on source IP addresses. The conventional solutions are unsatisfying—rotating proxy services charge hundreds of dollars monthly for residential IPs, managing your own VPS fleet requires infrastructure overhead, and Tor is too slow for practical reconnaissance work.

FireProx emerged from the red team community as an elegant hack: AWS API Gateway, designed for legitimate API management, happens to distribute requests across Amazon's vast infrastructure. Each HTTP request proxied through API Gateway originates from a different AWS IP address due to the service's load-balancing architecture. Instead of paying for proxy pools or maintaining servers, you're leveraging infrastructure AWS already runs. The tool wraps boto3 API calls in a simple CLI, transforming a multi-step AWS console configuration into single commands. For security researchers operating within legal boundaries, it's IP rotation with minimal cost and maximum convenience.

Technical Insight

Under the hood, FireProx creates AWS API Gateway REST APIs configured as HTTP proxies with a catch-all path variable. When you run the tool, it uses boto3 to programmatically construct an API Gateway endpoint with an ANY method (accepting all HTTP verbs) and a greedy path parameter {proxy+} that captures everything after the base URL. The integration type is set to HTTP_PROXY, which forwards requests to your target URL while preserving headers, query parameters, and request bodies.

Here's what a typical FireProx workflow looks like:

# Create a proxy endpoint for example.com
python fire.py --access_key YOUR_KEY --secret_access_key YOUR_SECRET \
  --region us-east-1 --command create --url https://example.com

# Returns:
# [proxy_id] (abc123def) => https://random123.execute-api.us-east-1.amazonaws.com/fireprox/

# Now use the proxy URL instead of the original:
curl https://random123.execute-api.us-east-1.amazonaws.com/fireprox/api/users
# This request hits example.com/api/users from an AWS IP

# List all your proxies
python fire.py --profile default --command list

# Delete when done
python fire.py --profile default --command delete --api_id abc123def

The clever part is how FireProx handles the X-Forwarded-For header problem. API Gateway automatically adds this header with your real IP, which would defeat the purpose. FireProx's solution: it provides an X-My-X-Forwarded-For custom header that you can set to any value. The tool's API Gateway configuration includes mapping templates that swap this custom header for the real X-Forwarded-For, allowing you to spoof source addresses in scenarios where the target checks forwarding headers.

The IP rotation happens naturally because API Gateway doesn't guarantee request routing to the same infrastructure nodes. Amazon's edge-optimized endpoints distribute across CloudFront locations, and even regional endpoints balance across availability zones. From the target's perspective, your requests come from different /16 or /24 CIDR blocks within AWS's IP space—enough diversity to bypass simple rate limiting that tracks requests per IP.

FireProx also implements resource tagging for management. Each created API Gateway gets tagged with {'Project': 'fireprox'}, making cleanup easier if you forget proxy IDs. The tool stores minimal state locally—just API IDs returned from AWS—while API Gateway itself maintains all configuration. This stateless design means you can run FireProx from different machines with the same AWS credentials and manage the same proxy fleet.

Cost efficiency comes from API Gateway's pricing model: $3.50 per million requests plus minimal data transfer fees. For typical reconnaissance activities generating thousands (not millions) of requests, your monthly bill might be under a dollar. Compare this to residential proxy services charging $500+ monthly, and the economic advantage becomes obvious—assuming you already have an AWS account and are operating within acceptable use policies.

Gotcha

The biggest limitation isn't technical—it's legal and policy-based. AWS's Acceptable Use Policy explicitly prohibits network abuse and unauthorized penetration testing. If you use FireProx against systems you don't own or have written authorization to test, and that target reports abuse to AWS, your account faces suspension or termination. The tool leaves a perfect audit trail: every API Gateway you create is logged in CloudTrail, linked to your AWS account, and associated with your payment method. This is not an anonymity tool; it's an IP rotation tool for authorized testing scenarios.

Sophisticated targets can detect and block API Gateway traffic. AWS publishes IP ranges publicly (available via their ip-ranges.json file), so any organization can blocklist all AWS addresses. CloudFlare and advanced WAFs often have "challenge AWS traffic" rules that treat API Gateway sources suspiciously. You're also limited to HTTP/HTTPS protocols—no SSH, database protocols, or WebSocket persistence. API Gateway's request timeout is 29 seconds maximum, so long-running operations will fail. Finally, some API Gateway features like custom domain names or VPC links could reduce IP diversity, defeating the rotation benefit if misconfigured.

Verdict

Use if: You're conducting authorized penetration testing, bug bounty research, or security assessments where you have explicit permission to test the target system. FireProx excels at bypassing basic IP-based rate limiting during reconnaissance phases, and the AWS cost is negligible compared to commercial proxy services. It's perfect for red team operations where the AWS account linkage is acceptable because you're operating legally. Skip if: You need true anonymity (the AWS paper trail is permanent), you're targeting sophisticated anti-bot systems that blocklist AWS IP ranges, you require non-HTTP protocols, or you're operating in legal gray areas. Also skip if your target uses CloudFlare with aggressive bot detection—you'll burn through API endpoints quickly as they get challenged or blocked. For those scenarios, invest in residential proxy services or accept Tor's performance limitations.