Smith: The Bug Bounty Wrapper That Makes Meg Actually Useful

Hook

Most security researchers abandon meg after their first scan because parsing thousands of HTTP responses manually is soul-crushing work. Smith exists because someone finally automated the boring part.

Context

In bug bounty hunting, reconnaissance is a volume game. You're testing hundreds or thousands of hosts for the same vulnerability patterns: CRLF injection endpoints, open redirects, subdomain takeovers, exposed sensitive files. Tools like meg excel at making massive numbers of HTTP requests in parallel—fetching many paths across many hosts efficiently. The problem? Meg dumps everything into files and leaves you to manually grep through potentially gigabytes of HTTP responses looking for vulnerability indicators.

This is where most reconnaissance workflows break down. You either write brittle bash one-liners that miss edge cases, or you spend hours manually reviewing responses. EdOverflow's smith emerged from this frustration in the bug bounty community. It's a purpose-built wrapper that packages common vulnerability wordlists with corresponding grep patterns, transforming meg from a raw HTTP fetcher into an opinionated reconnaissance pipeline. Instead of general-purpose fuzzing, smith optimizes for the specific workflows that actually produce results in web application security testing.

Technical Insight

Smith's architecture is deceptively simple—it's a single shell script that orchestrates meg and filters output—but this simplicity is intentional design. The tool operates in two modes: scanning (-s) to run meg against targets, and finding (-f) to parse previous results. This separation lets you scan once and experiment with different grep patterns later without hammering target infrastructure.

The scanning mode follows a consistent pattern for each vulnerability type. Here's how the CRLF injection scan works:

# From smith's source code
if [[ "$2" == "crlf" ]]; then
    echo "[*] Running meg with CRLF wordlist..."
    meg --verbose -c 50 wordlists/crlf.txt "$TARGET" crlf-output
    echo "[*] Sieving through results..."
    grep -Hnri "< Set-Cookie:" crlf-output/ | grep "%0d%0a" > crlf-findings.txt
    echo "[!] Potential CRLF injection points saved to crlf-findings.txt"
fi

This pattern reveals smith's core value proposition. It's not inventing new scanning techniques; it's codifying institutional knowledge. The grep pattern grep -Hnri "< Set-Cookie:" crlf-output/ | grep "%0d%0a" captures what experienced researchers know: CRLF vulnerabilities often manifest as injected headers, and URL-encoded CRLF sequences (%0d%0a) in Set-Cookie headers are high-confidence indicators. Without smith, every researcher would need to discover or remember this pattern independently.

The wordlists are equally opinionated. The CRLF wordlist contains paths with injected CRLF payloads like /%0d%0aSet-Cookie:crlfinjection=true appended to common parameters. The open redirect wordlist targets known redirect parameters (?url=, ?redirect=, ?next=) with test payloads. This curation eliminates the "which paths should I test?" decision paralysis that plagues reconnaissance workflows.

For subdomain takeover detection, smith takes a different approach because the vulnerability exists at the DNS/hosting level rather than in HTTP responses:

if [[ "$2" == "takeover" ]]; then
    meg --verbose -c 50 wordlists/takeover.txt "$TARGET" takeover-output
    grep -Hnri "NoSuchBucket\|No Such Account\|You're Almost There\|There isn't a GitHub Pages site here" takeover-output/ > takeover-findings.txt
fi

The grep pattern searches for error messages that indicate unclaimed resources—the telltale signs of subdomain takeover vulnerabilities. This demonstrates smith's pattern-matching philosophy: each vulnerability type has fingerprints in HTTP responses that experienced researchers recognize, and smith just automates that recognition.

The finding mode (-f) is where smith's separation of concerns pays dividends. After a scan completes, you can re-run the grep patterns without making new HTTP requests:

smithctl -f crlf

This searches through existing crlf-output/ files with the same grep logic. If you discover a better pattern or want to search for additional indicators, you can modify the script and re-analyze without waiting for meg to re-fetch responses. For large-scale reconnaissance across thousands of hosts, this dramatically accelerates iteration.

The tool's shell-based implementation means the entire workflow is transparent. There's no compiled binary or complex dependency chain—just bash, grep, and meg. Security researchers can read the source, understand exactly what it's doing, and modify it for their specific needs. This transparency is crucial in security tooling where blind trust is inappropriate.

Gotcha

Smith's greatest strength—being a simple wrapper—is also its fundamental limitation. The tool is completely dependent on meg, which hasn't been actively maintained in recent years. Meg itself has known issues with handling large response bodies, authentication, and rate limiting. Smith inherits all these problems and adds no mitigation. If meg fails to fetch a resource or crashes mid-scan, smith provides no recovery mechanism. You're debugging meg issues, not smith issues.

The grep patterns, while useful starting points, are also brittle. Security indicators evolve—cloud providers change error messages, applications implement new header structures, and edge cases emerge. Smith's patterns are hardcoded in the shell script, so adapting to new vulnerability variants requires forking and modifying the code. There's no plugin system or configuration file for extending patterns. Additionally, the grep approach produces false positives that require manual verification. A response containing the string "%0d%0a" doesn't automatically mean a vulnerability exists; context matters. Smith flags potential issues but can't validate exploitability, so you still need manual review skills. The tool also lacks any result deduplication, meaning identical findings across multiple hosts will appear repeatedly in output files.

Verdict

Use smith if: You're actively doing bug bounty reconnaissance, already have meg in your workflow, and waste time repeatedly running the same grep commands against meg output. It's genuinely useful for researchers who understand what it's testing and can validate findings manually. The pre-packaged patterns will save you time on 80% of common vulnerability checks. Skip if: You don't already use meg (start with httpx or nuclei instead—they're more actively maintained), need a production-grade tool with error handling and deduplication (build a custom pipeline with modern tooling), or expect the tool to validate vulnerabilities automatically (smith just flags patterns; you still need reconnaissance expertise). Also skip if you're testing a small number of targets where the overhead of learning meg and smith exceeds the time saved by automation.