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THREAT-Recon-CloudAssetShadowITDiscovery Sumo Logic CSE · Sumo

Detect Cloud Asset & Shadow IT Discovery via Internet-Wide Scanning Services in Sumo Logic CSE

Adversaries performing Search Open Technical Databases (T1596) rarely scan a target's network directly — instead they query commercial internet-wide scan-database services such as Shodan, Censys, BinaryEdge, ZoomEye, and ONYPHE, which continuously crawl the entire public IPv4/IPv6 space and index open ports, service banners, TLS certificates, and known CVEs for every internet-facing host. This lets an adversary map an organization's external attack surface — including forgotten dev/staging environments, misconfigured cloud storage endpoints, unmanaged VMs, and other 'shadow IT' the security team never inventoried — without sending a single packet the target can attribute to them. Because the adversary's actual query happens against the third-party database and is invisible to the defender, the only observable telemetry is the re-indexing traffic these scanning services' own crawler infrastructure generates as they continuously re-scan the internet to keep their databases current. This detection treats that crawler traffic as an early-warning signal: it flags (1) perimeter traffic from known scanning-service IP ranges probing many distinct ports on a single asset (the banner-grab pattern used to populate these databases), and, more importantly, (2) scanning-service traffic that reaches a destination IP absent from the organization's own asset inventory — meaning a commercial scan database has just indexed infrastructure the defender did not know was internet-facing. That second signal is functionally identical to what an adversary running T1596 would discover, giving defenders a chance to find and remediate the shadow IT asset before it is weaponized under T1190 (Exploit Public-Facing Application).

MITRE ATT&CK

Tactic
Reconnaissance

Sumo Detection Query

Sumo Logic CSE (Sumo)
sql
// Alert 1: Perimeter traffic from known internet-wide scanning service ranges touching multiple destination ports on one asset
_sourceCategory=network/firewall
| where cidr(src_ip, "198.20.69.0/24") or cidr(src_ip, "198.20.70.0/24") or cidr(src_ip, "198.20.71.0/24") or cidr(src_ip, "167.94.138.0/24") or cidr(src_ip, "167.94.145.0/24") or cidr(src_ip, "167.94.146.0/24") or cidr(src_ip, "162.142.125.0/24") or cidr(src_ip, "199.45.152.0/23") or cidr(src_ip, "199.45.154.0/23") or cidr(src_ip, "195.154.108.0/24")
| count_distinct(dest_port) as DistinctPorts, min(_messageTime) as FirstSeenMs, max(_messageTime) as LastSeenMs, count as HitCount by src_ip, dest_ip
| where DistinctPorts >= 5
| "ScannerBreadthProbe" as DetectionType
| fields LastSeenMs, src_ip, dest_ip, DistinctPorts, HitCount, DetectionType

// Alert 2: run as a separate scheduled search — scanner-sourced traffic reaching an asset not present in the KnownAssets lookup
_sourceCategory=network/firewall
| where cidr(src_ip, "198.20.69.0/24") or cidr(src_ip, "167.94.138.0/24") or cidr(src_ip, "162.142.125.0/24") or cidr(src_ip, "195.154.108.0/24")
| lookup asset_ip as dest_ip from known_assets_lookup on asset_ip
| where isNull(asset_ip)
| count as HitCount, count_distinct(src_ip) as DistinctSourceScanners, min(_messageTime) as FirstSeenMs, max(_messageTime) as LastSeenMs by dest_ip
| "ShadowAssetDiscoveredByScanner" as DetectionType
| fields dest_ip, HitCount, DistinctSourceScanners, FirstSeenMs, LastSeenMs, DetectionType
medium severity medium confidence

Two Sumo Logic searches for T1596 crawler traffic against firewall/network telemetry. The first matches known internet-wide scanning-service source ranges probing 5 or more distinct destination ports on a single asset. The second lookup-joins scanner-sourced traffic against a known_assets_lookup table and flags destination IPs with no match — surfacing unmanaged/shadow assets. Run as scheduled searches and combine into a single Sumo Logic dashboard panel.

Data Sources

Sumo Logic with firewall/network collectorSumo Logic Cloud SIEM (CSE) with network source

False Positives & Tuning

  • Authorized red team or third-party pentest infrastructure overlapping with commercial internet-scanning IP ranges
  • Uptime/monitoring SaaS providers probing multiple ports for health checks from ranges not yet allowlisted
  • Newly provisioned intentionally public-facing assets not yet added to the known_assets_lookup table

Other platforms for THREAT-Recon-CloudAssetShadowITDiscovery


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.

  1. Test 1Linux — Multi-Port TCP Connect Sweep Simulating Scanner Breadth Probe

    Expected signal: Perimeter firewall/NSG flow log entries (CommonSecurityLog or CEF equivalent) recording 15-20 distinct DestinationPort values from the test source IP to <TARGET_IP> within a short window, with an allow or deny verdict per port.

  2. Test 2Linux — HTTP Request Using Known Scan-Database Crawler User-Agent

    Expected signal: Web/application server access log entry for <TEST_WEB_HOST> recording the User-Agent string 'CensysInspect/1.1 (+https://about.censys.io/)' against the source IP that issued the request.

  3. Test 3Linux — Scanner Traffic Reaching an Asset Absent From the KnownAssets Watchlist

    Expected signal: Perimeter firewall/flow log entries for the test source IP reaching <SHADOW_TEST_IP> on the probed ports, with no corresponding entry for <SHADOW_TEST_IP> in the KnownAssets watchlist or known_assets.csv lookup.

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