Conference notes: The Bug Hunters Methodology v3(ish) (LevelUp 0x02 / 2018)

Hi, these are the notes I took while watching “The Bug Hunters Methodology v3(ish)” talk given by Jason Haddix on LevelUp 0x02 / 2018.

the-bug-hunters-methodology-v3.png

About

This talk is about Jason Haddix’s bug hunting methodology. It is an upgrade of:

Light reading

Recon & Enumeration

Discovering IP Space

Goal: Given an org name, identify both their hosts/top-level domains & IP space

ASN’s

  • ASN = Autonomous System Number
  • http://bgp.he.net
    • Enter a company name or a keyword => ASNs listed, select 1 => IP ranges listed in Prefixes v4 tab
    • One of the only sites that support search by keyword (e.g. tesla, tesla motors, tesla inc…)

ARIN & RIPE

Rev WHOIS

Shodan Organization

Discovering New Targets (Brands & TLDs)

Goal: Find new brands & Top-Level Domains

Brand/TLD Discovery

Acquisitions

Linked discovery

  • Burp spidering
    • Demo (min 14.45)
      1. Turn off passive scanning (it generates a lot of results, taking up a lot of memory because we’re gonna spider a lot of sites) - Scanner > Live Passive Scanning > Check Don’t scan
      2. Set forms to auto submit (if feeling frisky)
        • Spider tab > Application login section > Check Handle as ordinary form burp-spider-1.png
        • Spider tab > Form submission section > Automatically submit using the following rules… burp-spider-2.png
        • If you submit regular form & there’s an email generating form, you would blast tesla
        • So use your discretion to configure these 2 forms. If it’s a small site with no email generating form, it’s OK to enable automatic forms submission
      3. Set scope to advanced control & use string of target name (not a normal FQDN)
        • Goal: Show only links that have tesla in the URL in the Site map burp-spider-3.png burp-spider-4.png
        • Click yes for to “…stop sending out of scope items to the history…”
        • Show only in scope items in the Target / Site map
      4. Manually walk + browse, then spider all hosts recursively
        • Spidering can take 5 to 25 min depending
      5. profit (more targets)!
  • Domlink
    • by Vincent Yiu
    • Idea: Recursively looks at reverse whois programmatically based on who registered a domain, and then creates a link between those domains
    • Usage: python ./domLink.py -d vip.com -o vip.out.txt
      • Do a whois lookup on vip.com. Then from the WHOIS information, based on the registrar & other data, recursively look at any other WHOIS record that has the same information
    • Hasn’t worked well for Jason yet but he likes the idea
  • Builtwith
    • Idea: Links together the relationship of a site based on its analytics trackers (ie domains using the same analytics code)
    • Usage: Relationships tab, Related Domains section
      • Gives you a heat map of how each domain is related to your target
    • Helped him find sites that are related and in scope but not explicitly listed

Others

  • Google dork for:
    • the Trademark of the company: "Tesla © 2016" "Tesla © 2015" "Tesla © 2017" inurl:tesla or whatever trademark is at the bottom of the page
    • the privacy policy link of the company

Discovering new targets (Subdomains)

  • Goal: Finding subdomains
  • Two main ways:
    • Subdomain scraping: Find subdomains referenced online somewhere
    • Subdomain brute forcing: Try to resolve subdomains based on a wordlist

Subdomain scraping

  • It’s all about sources
  • Probably 25 to 40 good sources. Examples:
    • Ask.com
    • crt.sh
    • Hacker target
    • https://dnsdumpster.com
    • Ptrarchive.com
    • DNSDB Search
    • Bing
    • Baidu
    • Yahoo!
    • Google
    • Robtex!
    • Censys
    • CertDB
    • Cert Spotter
    • Netcraft
    • Passive Total
    • F-secure Riddler
    • Dogpile
    • Security Trails
    • ThreatMiner
    • VirusTotal
    • Wayback Machine
    • ThreatCrowd
  • Tools you use must have the right sources and be executed relatively quickly
  • Jason used to use Sublist3r & Altdns but now prefers using only Amass & Subfinder
Amass
  • https://github.com/caffix/amass by @jeff_foley
  • Up to 22 sources
  • Includes Reverse DNS methods & permutation scanning (dev-1.netflix.com, dev-2.netflix.com)
  • Usage
[email protected]:~/tools/amass# cat amass.sh
#!/bin/bash
mkdir $1
touch $1/$1.txt
amass -active -d $1 |tee /root/tools/amass/$1/$1.txt
[email protected]:~/tools/amass# ./amass.sh netflix.com
Subfinder
  • https://github.com/ice3man543/subfinder by Iceman
  • Most sources included in Amass
  • But also include Json output & a multi resolver for bruteforce…
  • Idea: Integrate scraping & bruteforcing in a single subdomain tool
  • Usage
    [email protected]:~/tools/subfinder# cat subfinder.sh
    #!/bin/bash
    mkdir $1
    touch $1/$1.txt
    subfinder -d $1 |tee /root/tools/subfinder/$1/$1.txt
    [email protected]:~/tools/subfinder# ./subfinder.sh twitch.tv
    
Amass & Subfinder are enough
  • Their output is comparable. So script them together on the CLI, then sort and unique the output
  • Used together, they cover about 30 sources
  • Amass can run a little bit longer than subfinder if you include the permutation scanning but not too long to impact your workflow
  • Other tools Jason used to use but not anymore:
    • Enumall / Recon-NG (not great on sources or speed)
    • Aquatone (not great on sources) but aquatone-scan is useful
    • Sublist3r (same as above)
    • Anything else for scraping
    • ClouDflare Enum (although sometimes he “thinks about it”)
      • He doesn’t use it but finds it interesting because he doesn’t understand the black magic behind how it works
      • Not sure if it uses sources better than Amass & Subfinder but he doesn’t think so

Subdomain Brute Forcing

  • Old tools:
    • Fierce
    • Blacksheepwall
    • Dns-parellel-prober
    • Knock.py
  • They’ve been supplanted by Massdns
    • Can run a million line dictionary in 30 sec
    • Because it’s written in C and breaks up your wordlist into small pieaces & assigns each piece to a different DNS resolver in Parallel
  • Subfinder also uses multiple DNS resolvers
    • Might be as good as Massdns but Jason hasn’t tried it yet for bruteforcing
  • CommonSpeak
    • By @naffy & @shubs
    • Content discovery wordlists built with BigQuery
    • Subdomain data is awesome, Jason plans on adding it to all.txt
    • But the URL data (URL paths) for content discovery has been less useful. It’s very app specific
    • So Jason uses CommonSpeak for subdomain data but not URL data
    • He also uses scans.io
Jason’s setup
  • Use Massdns
    • time ./subbrute.py /root/work/bin/all.txt $TARGET.com | ./bin/massdns -r resolvers.txt -t A -a -o -w massdns_output.txt -
  • Try Subfinder
  • Use Gobuster as the best non multi-resolver tool
    • time gobuster -m dns -u $TARGET.com -t 100 -w all.txt
  • Environment setup:
    • DigitalOcean
    • $10/mo offer (1 GB RAM, 1 CPU, 30 GB SSD, 2TB transfer)
    • Ubuntu 16.04 LTS
  • Subdomains wordlist to use: all.txt
  • Also use CommonSpeak & scans.io for subdomain data
Other methods of finding subdomains

Enumerating targets

Port Scanning

  • Use Masscan
    • By Robert Graham
    • Fastest port scanner. Nmap takes forever if you do a full port scan on all hosts of an ASN
    • Usage: masscan -p1-65535 -iL $TARGET_LIST --max-rate 10000 -oG $TARGET_OUTPUT
  • Shell script to run dig on a domain, strip out the HTTP/HTTPS prefix then run Masscan
    • Because Masscan takes only IPs as input, not DNS names
    • Use it to run Masscan against either a name domain or an IP range
      #!/bin/bash
      strip=$(echo $1|sed 's/https\?:\/\///')
      echo ""
      echo "##################################################"
      host $strip
      echo "##################################################"
      echo ""
      masscan -p1-65535 $(dig +short $strip|grep -oE "\b([0-9]{1,3}\.){3}[0-9]{1,3}\b"|head -1)
      --max-rate 1000 |& tee $strip_scan
      

Credential bruteforce

Masscan -> Nmap service scan-og -> Brutespray credential bruteforce

  • Use Masscan with the -oG option to get an output in Nmap format
  • Re-scan the output with Nmap version scanning
  • Pass the output to Brutespray which will bruteforce any remote administration protocol found with default & common passwords, and anonymous logins
  • Usage: python brutespray.py --file nmap.gnmap -U /usr/share/wordlist/user.txt -P /usr/share/wordlist/pass.txt --threads 5 --hosts 5

Visual identification

  • Not all subdomains previously scraped off the internet are still up, some are the same (DNS redirects) & we don’t know which protocol they ate on (HTTP or HTTPS)
  • We could port scan ports 80 & 443
  • But another way to find out what is up and unique is taking screenshots with Eyewitness

Eyewitness

  • Eyewitness takes a list of domains without a protocol, visits each one with a headless browser, takes a screenshot & dumps them to a report
    • Usage: python Eyewitness.py --prepend-https -f ../domain/tesla.com.lst --all-protocols --headless
    • => tells you which domains redirect to the same app, which domains are interesting & should be hacked first
  • Why not Aquatone or Httpscreenshot: Because Eyewitness tries both HTTP & HTTPS protocols
  • Eyewitness isn’t foolproof: The headless browser doesn’t always resolve, timeout issues, it can take a while…
  • => Use Eyewitness for large targets.
  • => But if you have a small list (~20 hosts), use sed or awk to add HTTP & HTTPS to every subdomain, then load them up manually with the CLI in the browser
  • Or use OpenList, a Chrome extension: Give it your list of URLs & it’ll open them in multiple tabs

What to look for?

Not interesting:

  • Anything that redirects to the main site
  • Help portal, email portal or OWA portal. They’re usually hardened out of the box (not always but most of them time)

Interesting:

  • Custom apps that are not the main website
    • They’ve probably spent less time with security on those sites than the main domain

Non standard Web ports:

  • There’s a list of ~20 very common non-standard Web ports (i.e. services not running on port 80 or 443)
  • You can find them by port scanning with Masscan & service scanning with Nmap
  • Then add them to Eyewitness with the --add-http-ports or --add-https-ports options.

Wayback enumeration

wayback2.jpg wayback.jpg

  • Also useful when you find subdomains that look juicy but don’t resolve
  • Example: Site protected with Basic Auth but an old version cached by Wayback Machine has configuration information of a server on the front page.
  • Tools

Platform Identification & CVE searching

  • Retire.js: Outdated libraries (cmd-line, Burp on online form)
  • Builtwith: Stack information profiling
  • Wappalyzer: Similar to Builtwith (cmd-line, browser extension or online form)
  • burp-vulners-scanner: Burp plugin, detects versions with CVEs

  • A lot of memory is needed to use many Burp extensions on large scope bounties !

Parsing JavaScript

  • Generally automation doesn’t handle JavaScript very well
  • You could parse JS files manually but it’s not possible on large scope bounties
  • Many people assume Burp automatically parses JS files, relative paths, etc, and is able to execute all JS it finds. Burp is good but not perfect for this
  • Tools for better coverage of heavy JS sites:
    • ZAP Ajax Spider
      • Basically spiders the site with a headless browser zap.jpg
    • LinkFinder
      • Extracts absolute & relative URLs from JS files
    • JSParser
      • Burp pro only
      • Similar to LinkFinder but not as good
  • Feeding these tool:
    1. Right click on any domain, choose Engagement tools then Find scripts. Clic on Search (finds all references to JS in all scripts) and Copy selected URLs
    2. Pass URLs found to one of the JS tools
    3. Visit the new URLs links these tools found in JS scripts

Content discovery / Directory bruting

  • Idea: Bruteforcing URL paths
  • His favorite content discovery tool & wordlist
    • Gobuster
      • The tool he uses because it’s in Go, fast & is extensible
      • time ./gobuster -w --seclists/Discovery/Web_Content/raft-large-words.txt -s 200,301,307 -t 100 -u https://www.tesla.com
    • content_discovery_all.txt
      • Includes both files & URL paths
      • Includes Robots disallowed & Raft
      • Robots disallowed & Raft are old but still really useful
      • He prefers them to scan.io data or other lists because:
        • Robots disallowed & raft parsed all the robots.txt files on the Internet & sorted by occurrence the paths that people didn’t want you to visit
        • scans.io data parses whole websites & gives you occurrences of files & paths so it’s not stuff that they don’t want you to find, just occurrence or URLs => not useful for a pentester/bug hunter
  • Other tools
  • Other wordlists

Parameter bruting?

Summary of the whole recon methodology

recon-summary.png

Common vulnerabilities

XSS

  • Not a lot of changes
  • 2 new super useful frameworks for instrumenting Blind XSS:
    • bXSS: has SMS support for notifications
    • ezXSS

Server Side Request Forgery (SSRF)

  • Nothing new about the method of testing
  • When testing against a cloud environment, what do you look for?
    • cloud_metadata.txt: Contains for each cloud provider (AWS, Google Cloud, Packetcloud, OpenStack…), a list of URLs to their internal metadata services & what you can get from each URL.

Insecure Direct Object Reference

IDOR - MFLAC

  • One of the most common bug classes he sees across Bugcrowd as far as occurrence & severity
  • Pay attention to:
    • all numeric IDs
    • anything that looks like a hash
    • anything that looks like an email that you could change to something else so that you can get access to somebody else’s account

Common locations of IDOR bugs/vulns

{regex + perm} id {regex + perm} user  
{regex + perm} account {regex + perm} number  
{regex + perm} order {regex + perm} no  
{regex + perm} doc {regex + perm} key  
{regex + perm} email {regex + perm} group  
{regex + perm} profile {regex + perm} edit REST numeric paths

Example: http://acme.com/script?user=21856

Infrastructure & Config

Subdomain takeover

  • Cloud providers
    • Heroku
    • Github
    • Tumblr
    • Shopify
    • Squarespace
    • Salesforce Desk
    • Amazon Webservices
    • Unbounce
    • Uservoice
    • SurveyGizmo
    • Fastly
    • Zendesk
    • Instapage
    • Dyn
    • Amazon Cloudfront
    • HubSpot
    • FastMail
    • WPengine
  • Check for CNAMES that resolve to these services. If the service has lapsed, register & profit!
  • can-i-take-over-xyz: List of every service, if it’s possible to do subdomain takeover and how & the fingerprint when there is no service registered

Robbing misconfigured sh** (AWS)

  • S3Scanner
    • Tool to find open buckets related to your target company
    • Give it a file with sources of either the full URL, the bucket region, just a domain name or a bucket name

WAF

  • It’s common for bug hunters to get banned by WAF or CDN vendors security products
    • Predominant WAFs: Cloudflare & Akamai
    • Dedicated WAFS
  • Solutions
    • Encoding (Meh)
    • Finding origin akamai.jpg
    • Finding dev
    • If a WAF blocks you on domain.com, try bypassing it by going to:
      • dev.domain.com
      • stage.domain.com
      • ww1/ww2/ww3…domain.com
      • www.domain.uk/jp/… (regionalized domains)
    • Even though they serve the same app, the WAF might not be configured to protect those domains waf.jpg

Xmind Organization

  • Using this semi automatic methodology, you’ll end up with a lot of artifacts from a lot of tools.
  • => It’s hard to track a large scope bounty well
  • Many people use Burp Highlighting or Burp’s inline tools to keep track of this stuff
  • But Jason prefers Mind mapping with Xmind to track all his tool usage & progress
  • Example:

xmind-1.jpg

  • oos = Out Of Scope

xmind-2.jpg

  • Linked Discovery (raw), amass (raw)… : raw output of the tools
  • Live: The actual site he’s testing
  • Color highlighting
    • Green w/ checkmark = Done
    • Orange = Progress
    • Red = Vulnerable xmind-3.png
  • Markdown template: Templates for all his common findings on this bug bounty program (you’ll often find the same vuln accross multiple hosts on large scope bounties)

The future of TBHM

  • Bugcrowd University is the future of TBHM
  • It’s a new training course including all information in TBHM slides + new topics
  • An open source training curriculum for each bug class
  • New content will be released every quarter
  • You can contribute to the open source slides, present them in local meetups or null/Defcon meetups
  • Initial topics will be:

bugcrowd-university.png

  • Intermediate level: P1 bugs submitted by super hunters that get paid out really high

See you next time!


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