Detect AI/LLM Crawler Bot Robots.txt Exclusion Violation and User-Agent Spoofing in Sumo Logic CSE
Adversaries and unauthorized data harvesters increasingly abuse AI/LLM crawler bots — GPTBot, ChatGPT-User, OAI-SearchBot, CCBot, ClaudeBot, PerplexityBot, Bytespider, Amazonbot, Google-Extended, Applebot-Extended, and similar answer-engine/AI-training crawlers — either by exploiting these crawlers' inconsistent enforcement of robots.txt Disallow directives, or by directly spoofing their User-Agent strings from unverified IP space to blend reconnaissance traffic in with 'legitimate' AI bot noise. Because these crawlers exist specifically to harvest and re-publish or re-embed site content into search indexes and LLM training/retrieval pipelines, a crawler (or an actor impersonating one) that walks Disallow-listed or otherwise sensitive paths — admin panels, internal API routes, staging environments, exposed configuration files — represents both a reconnaissance risk (site structure and sensitive-path discovery feeding follow-on targeting) and a data-exposure risk (disallowed content ingested into a third-party AI pipeline outside the organization's control). This is a variant of Search Engines reconnaissance (T1593.002) specific to the AI-crawler ecosystem: unlike traditional search engine bots (Googlebot, Bingbot) which have long-published, verifiable IP ranges and generally respect robots.txt, many AI-crawler vendors have inconsistent or unpublished IP verification, making UA-string spoofing a low-effort way for reconnaissance tooling to masquerade as benign traffic.
MITRE ATT&CK
- Tactic
- Reconnaissance
Sumo Detection Query
_sourceCategory=*web* OR _sourceCategory=*iis* OR _sourceCategory=*apache*
| parse regex "(?<client_ip>\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}) - .* \"(?<method>[A-Z]+) (?<uri>[^ ]+).*\" (?<status>\\d+) .* \"(?<referer>[^\"]*)\" \"(?<user_agent>[^\"]*)\""
| where user_agent matches "*GPTBot*" or user_agent matches "*ClaudeBot*" or user_agent matches "*PerplexityBot*" or user_agent matches "*Bytespider*"
| where uri matches "*/admin*" or uri matches "*/internal*" or uri matches "*/.git*" or uri matches "*/backup*" or uri matches "*/.env*"
| count by client_ip, user_agent, uri
| sort by _count descSumo Logic detection for AI/LLM crawler robots.txt exclusion abuse (variant of T1593.002). Uses _sourceCategory path filtering for flexible log routing, with field extraction and aggregation to surface AI-crawler UAs hitting Disallow-listed or sensitive paths. Designed for the Sumo Logic Cloud SIEM platform.
Data Sources
Required Tables
False Positives & Tuning
- Legitimate AI crawlers requesting a Disallow-listed path shortly after a robots.txt update, before the new rules have propagated to the crawler
- SEO auditing or bot-simulation QA tooling intentionally spoofing AI-crawler User-Agent strings during authorized testing
- Authorized security researchers testing robots.txt enforcement and bot-detection controls under an approved engagement
Other platforms for THREAT-Recon-AICrawlerRobotsExclusionAbuse
Testing Methodology
Validate this detection against 3 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1AI Crawler User-Agent Spoofing Against Disallowed Paths (Linux)
Expected signal: Web server access logs showing sequential GET requests to Disallow-listed paths from the same source IP within seconds, all bearing a GPTBot User-Agent string. IIS W3CIISLog: cIP=attacker_ip, csUserAgent contains 'GPTBot', csUriStem matching each disallowed path. Apache/Nginx access_combined: equivalent fields.
- Test 2Burst Simulated AI-Crawler Traffic Rate Test (Linux/macOS)
Expected signal: Web server access logs showing 320 requests from a single source IP within a short window (well under 10 minutes), all bearing a PerplexityBot User-Agent string. IIS W3CIISLog and Apache/Nginx access logs both capture the request volume, source IP, and User-Agent per request.
- Test 3AI Crawler Spoofing via PowerShell (Windows)
Expected signal: Sysmon Event ID 1: powershell.exe process with Invoke-WebRequest in CommandLine. Sysmon Event ID 3: outbound network connections from powershell.exe to the target server. Victim-side web server access logs (IIS W3CIISLog) capturing the ClaudeBot User-Agent against each Disallow-listed path with source IP and response code.
References (5)
- https://attack.mitre.org/techniques/T1593/002/
- https://platform.openai.com/docs/bots
- https://www.cloudflare.com/learning/bots/how-to-manage-ai-bots/
- https://developers.google.com/search/docs/crawling-indexing/google-extended
- https://learn.microsoft.com/en-us/azure/azure-monitor/reference/tables/w3ciislog
Response Playbook
Triage
- Extract the source IP and claimed AI-crawler identity from the User-Agent header; attempt reverse-DNS resolution and compare against the vendor's officially published IP/CIDR ranges where available (OpenAI publishes GPTBot ranges at openai.com/gptbot.json; Google publishes Google-Extended ranges via its standard Googlebot verification feed). Many AI-vendor crawlers (ClaudeBot, PerplexityBot, Bytespider) do not currently publish verifiable ranges — treat unverifiable claims as inherently higher-risk by default
- Determine which Disallow-listed or sensitive path was accessed and whether the response was successful (scStatus=200) with a meaningful payload size (scBytes > 200) — a successful retrieval means content was actually ingested rather than just probed
- Review whether this is an isolated single-page fetch (consistent with a one-off crawler bug or caching delay) or a systematic walk of many distinct Disallow-listed paths in a short window (consistent with intentional reconnaissance dressed up as a compliant crawler)
- Cross-reference the source IP/ASN against known cloud and hosting-provider ranges (AWS, Azure, GCP, DigitalOcean, OVH) commonly used to spin up spoofed-UA scanning infrastructure that hides among legitimate AI-vendor traffic noise
- Check whether robots.txt was recently modified — a spike in violations immediately following a robots.txt update most often indicates the crawler has not yet re-fetched the new file (benign propagation delay) rather than deliberate evasion
Containment
- If the source IP fails vendor-range verification, challenge or block it at the WAF/CDN layer (Cloudflare verified-bot list, AWS WAF Bot Control, Azure Front Door bot rules) rather than trusting the raw User-Agent string
- Pair robots.txt with an actual server-side access-control layer — return HTTP 403 for Disallow-listed paths regardless of the requesting UA, since robots.txt is advisory-only and any client (human or bot) can freely ignore it
- For confirmed spoofed-UA scanning traffic, add the source IP/ASN to a blocklist and rate-limit any request whose UA claims to be a major AI crawler but originates outside that vendor's published (or reverse-DNS-verifiable) infrastructure
- If sensitive content was confirmed retrieved by a legitimate but non-compliant AI crawler, pursue the vendor's published opt-out/content-removal process and update robots.txt Disallow rules; note that removal from an existing training corpus is frequently not possible after the fact
Evidence Collection
- Full web server access logs (IIS W3CIISLog / Apache/Nginx access_combined) capturing User-Agent, source IP, requested path, response code, and bytes transferred for the entire session window
- WAF/CDN bot-management logs (Cloudflare Bot Management, AWS WAF Bot Control) which often include a computed 'verified bot' classification independent of the raw User-Agent string
- robots.txt version history (git log or web server file modification timestamps) to establish exactly which Disallow rules were in force at the time of the observed access
- DNS / reverse-DNS (PTR) resolution records for the source IP captured at the time of access, to support after-the-fact vendor-identity verification
Escalation Criteria
- !Confirmed successful retrieval (HTTP 200, non-trivial byte count) of a Disallow-listed sensitive path by a UA claiming AI-crawler identity that fails vendor IP-range or reverse-DNS verification
- !Systematic enumeration of many distinct Disallow-listed paths from a single source IP within a short window, inconsistent with normal incremental crawling behavior
- !The same source IP or UA pattern is subsequently observed in connection with follow-on techniques — exploitation of a discovered endpoint (T1190), further OSINT correlation (T1589/T1590), or credential-stuffing against a discovered login path
- !Violations continue well past a robots.txt update's normal propagation window (>72 hours), ruling out simple caching delay as an explanation
Investigation Guide
Related Techniques
Forensic Artifacts
- >
Web server access logs with User-Agent, source IP, and requested path — IIS: %SystemDrive%\inetpub\logs\LogFiles\W3SVC*; Apache: /var/log/apache2/access.log; Nginx: /var/log/nginx/access.log - >
robots.txt file and its version-control history, establishing which Disallow rules were in effect at the time of access - >
WAF/CDN bot-management classification logs (Cloudflare, Akamai, Fastly) that independently score/verify bot identity beyond the raw User-Agent string - >
Vendor-published crawler IP-range documents (e.g. openai.com/gptbot.json, Google's Google-Extended verification feed) captured at incident time for after-the-fact verification, since these ranges change over time - >
DNS resolution / PTR records for the source IP at the time of access
Tuning Guidance
This detection carries inherently low baseline confidence because User-Agent strings are trivially forgeable and, unlike Googlebot/Bingbot, several major AI-crawler vendors do not publish comprehensive, easily-automatable IP verification ranges. To reduce false positives: (1) build and maintain an allowlist of verified vendor IP ranges where published (OpenAI's gptbot.json, Google's Google-Extended feed) and suppress alerts for verified-range traffic; (2) for vendors without published ranges (ClaudeBot, PerplexityBot, Bytespider), rely on the burst/systematic-enumeration heuristics rather than UA string alone; (3) exclude your organization's own internal QA/bot-simulation tooling and known authorized SEO/pentest vendor IP ranges; (4) add a minimum response-size threshold (scBytes > 200) to the robots_exclusion_violation branch to focus on successful content retrieval rather than 403/404 noise; (5) correlate with follow-on technique detections — if the same source IP later appears in T1190 (exploit public-facing application) or T1110 (brute force) alerts within 48 hours, raise confidence to high. Consider serving canary content at a Disallow-listed path (a honeytoken page with a unique tracking string) — any AI-crawler ingestion of that content that later surfaces in a public LLM response is unambiguous confirmation of exclusion-bypassing behavior.
Hunting Queries
Hunt for source IPs presenting an AI-crawler User-Agent that access two or more distinct Disallow-listed/sensitive paths within a 60-minute window. Genuine paced crawling rarely walks multiple sensitive paths in quick succession; this pattern is consistent with either a misbehaving crawler ignoring exclusions or a reconnaissance actor spoofing the UA to blend in. Prioritize results where SuccessfulRequests > 0, indicating content was actually retrieved.
// Hunt for AI-crawler UAs accessing multiple distinct Disallow-listed paths from one IP in a short window
W3CIISLog
| where TimeGenerated > ago(7d)
| where csUserAgent has_any ("GPTBot", "ChatGPT-User", "CCBot", "ClaudeBot", "PerplexityBot", "Bytespider", "Amazonbot", "Google-Extended")
| where csUriStem has_any ("/admin", "/wp-admin", "/internal", "/staging", "/api/internal", "/.git", "/backup", "/private", "/config", "/.env")
| summarize DistinctPaths=dcount(csUriStem), TotalRequests=count(), Paths=make_set(csUriStem, 25), SuccessfulRequests=countif(scStatus == 200), EarliestAccess=min(TimeGenerated), LatestAccess=max(TimeGenerated) by cIP, csUserAgent
| where DistinctPaths >= 2
| extend WindowMinutes=datetime_diff('minute', LatestAccess, EarliestAccess)
| where WindowMinutes <= 60
| sort by DistinctPaths desc, SuccessfulRequests descindex=web (sourcetype=iis OR sourcetype=access_combined)
| eval ua_lower=lower(cs_user_agent)
| eval uri_lower=lower(cs_uri_stem)
| where match(ua_lower, "(gptbot|chatgpt-user|ccbot|claudebot|perplexitybot|bytespider|amazonbot|google-extended)")
| where match(uri_lower, "(/admin|/wp-admin|/internal|/staging|/api/internal|/\.git|/backup|/private|/config|/\.env)")
| bin span=1h _time
| stats dc(uri_lower) as DistinctPaths, count as TotalRequests, values(uri_lower) as Paths, sum(eval(if(sc_status=200,1,0))) as SuccessfulRequests, min(_time) as EarliestAccess, max(_time) as LatestAccess by c_ip, cs_user_agent, _time
| where DistinctPaths >= 2
| sort - DistinctPaths, - SuccessfulRequestsHunt for a single source IP generating an unusually high volume of requests (>300) while claiming an AI-crawler identity within a tight 10-minute window. Legitimate AI-vendor crawling is generally distributed across many IPs and rate-paced; a concentrated single-IP burst is a strong indicator of a spoofed User-Agent driving automated scanning or scraping rather than genuine vendor infrastructure.
// Hunt for single-IP request bursts claiming AI-crawler identity, inconsistent with distributed vendor infrastructure
W3CIISLog
| where TimeGenerated > ago(7d)
| where csUserAgent has_any ("GPTBot", "ChatGPT-User", "CCBot", "ClaudeBot", "PerplexityBot", "Bytespider", "Amazonbot")
| summarize RequestCount=count(), FirstSeen=min(TimeGenerated), LastSeen=max(TimeGenerated) by cIP, csUserAgent
| extend WindowMinutes=datetime_diff('minute', LastSeen, FirstSeen)
| where RequestCount > 300 and WindowMinutes < 10
| sort by RequestCount descindex=web (sourcetype=iis OR sourcetype=access_combined)
| eval ua_lower=lower(cs_user_agent)
| where match(ua_lower, "(gptbot|chatgpt-user|ccbot|claudebot|perplexitybot|bytespider|amazonbot)")
| bin span=10m _time
| stats count as RequestCount by c_ip, cs_user_agent, _time
| where RequestCount > 300
| sort - RequestCountAtomic Red Team Tests
Simulates a reconnaissance actor spoofing a major AI-crawler User-Agent string (GPTBot) while directly probing Disallow-listed and sensitive paths that a compliant crawler would never request. Run against your own authorized test web server only.
Command
TARGET="http://localhost:8080" # Replace with your authorized test server URL
DISALLOWED_PATHS=(
"/admin"
"/wp-admin"
"/internal"
"/staging"
"/api/internal"
"/.git/config"
"/backup"
"/private"
"/config"
"/.env"
)
echo "[*] Spoofing GPTBot User-Agent against ${#DISALLOWED_PATHS[@]} Disallow-listed paths"
for path in "${DISALLOWED_PATHS[@]}"; do
RESPONSE=$(curl -s -o /dev/null -w "%{http_code} %{size_download}" -A 'Mozilla/5.0 (compatible; GPTBot/1.1; +https://openai.com/gptbot)' "${TARGET}${path}")
echo "[${RESPONSE}] ${path}"
doneExpected Telemetry
Web server access logs showing sequential GET requests to Disallow-listed paths from the same source IP within seconds, all bearing a GPTBot User-Agent string. IIS W3CIISLog: cIP=attacker_ip, csUserAgent contains 'GPTBot', csUriStem matching each disallowed path. Apache/Nginx access_combined: equivalent fields.
Expected Detection
KQL RobotsViolation branch fires on each individual probe where csUserAgent has_any AICrawlerUserAgents and csUriStem has_any DisallowedPaths. SPL detection_branch=robots_exclusion_violation fires equivalently. The multi-path hunting query fires once 2+ distinct Disallow-listed paths are hit from the same source IP within an hour.
Simulates a spoofed-UA reconnaissance burst — a single source rapidly issuing hundreds of requests while claiming a PerplexityBot identity, inconsistent with the paced, distributed behavior of genuine vendor crawler infrastructure. Run against your own authorized test web server only.
Command
TARGET="http://localhost:8080" # Replace with your authorized test server URL
echo "[*] Issuing burst of 320 requests spoofing PerplexityBot identity"
for i in $(seq 1 320); do
curl -s -o /dev/null -A 'Mozilla/5.0 (compatible; PerplexityBot/1.0; +https://perplexity.ai/perplexitybot)' "${TARGET}/?probe=${i}" &
if (( i % 40 == 0 )); then wait; fi
done
wait
echo "[*] Burst complete"Expected Telemetry
Web server access logs showing 320 requests from a single source IP within a short window (well under 10 minutes), all bearing a PerplexityBot User-Agent string. IIS W3CIISLog and Apache/Nginx access logs both capture the request volume, source IP, and User-Agent per request.
Expected Detection
KQL BurstSpoofSuspect branch fires once RequestCount > 300 within a 10-minute window for a single cIP/csUserAgent pair. SPL detection_branch=burst_spoof_suspect fires equivalently on the RequestCount>300 condition. The burst hunting query surfaces the source IP with RequestCount > 300.
Simulates the same Disallow-path probing behavior from a Windows host using PowerShell's Invoke-WebRequest with a spoofed ClaudeBot User-Agent, representing a Windows-based reconnaissance tool masquerading as an AI-vendor crawler. Run against your own authorized test web server only.
Command
$target = "http://localhost:8080" # Replace with your authorized test server URL
$disallowedPaths = @("/admin", "/wp-admin", "/internal", "/staging", "/api/internal", "/backup", "/private", "/config")
Write-Host "[*] Spoofing ClaudeBot User-Agent against $($disallowedPaths.Count) Disallow-listed paths"
foreach ($path in $disallowedPaths) {
try {
$response = Invoke-WebRequest -Uri "$target$path" -UserAgent 'Mozilla/5.0 (compatible; ClaudeBot/1.0; [email protected])' -TimeoutSec 10 -UseBasicParsing
Write-Host "[$($response.StatusCode)] $path"
} catch {
Write-Host "[ERR] $path - $($_.Exception.Message)"
}
}Expected Telemetry
Sysmon Event ID 1: powershell.exe process with Invoke-WebRequest in CommandLine. Sysmon Event ID 3: outbound network connections from powershell.exe to the target server. Victim-side web server access logs (IIS W3CIISLog) capturing the ClaudeBot User-Agent against each Disallow-listed path with source IP and response code.
Expected Detection
Victim-side KQL RobotsViolation / SPL robots_exclusion_violation branches fire per-request identically to the Linux variant, since detection logic keys on User-Agent and URI path rather than client OS. The PowerShell execution itself may separately trigger T1059.001 detection rules if command-line auditing is enabled.