Detect SolarWinds Serv-U Uncontrolled Resource Consumption (CVE-2026-28318) in Sumo Logic CSE
Detects exploitation of CVE-2026-28318, an uncontrolled resource consumption vulnerability (CWE-400) in SolarWinds Serv-U. This vulnerability is listed in CISA's Known Exploited Vulnerabilities catalog and allows attackers to exhaust server resources, leading to denial of service conditions. Detection focuses on abnormal connection patterns, resource exhaustion indicators, and anomalous request volumes targeting Serv-U services.
MITRE ATT&CK
- Tactic
- Impact
Sumo Detection Query
_sourceCategory=network OR _sourceCategory=firewall OR _sourceCategory=servu
| where dest_port in ("21", "22", "990", "989", "443", "80") OR _sourceName matches /[Ss]erv-?[Uu]/
| timeslice 5m
| count as connection_count by _timeslice, dest_ip, dest_port, src_ip
| where connection_count > 500
| sort by connection_count desc
| fields _timeslice, src_ip, dest_ip, dest_port, connection_count
| if (connection_count > 2000, "critical", if (connection_count > 1000, "high", "medium")) as severitySumo Logic query monitoring network traffic to Serv-U service ports, alerting on connection floods exceeding 500 within 5-minute windows to detect CVE-2026-28318 resource exhaustion exploitation.
Data Sources
Required Tables
False Positives & Tuning
- Enterprise backup solutions creating many parallel FTP connections
- Automated CI/CD pipelines deploying files via SFTP generating connection bursts
- Security assessment tools performing authorized port scanning
- High-volume content distribution using Serv-U as a transfer endpoint
Other platforms for CVE-2026-28318
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 1Simulated FTP Connection Flood to Serv-U (Linux)
Expected signal: Network flow logs showing 600+ connection attempts from the test host to port 21 of the target within a short window; firewall logs recording SYN flood or connection rate spike; Serv-U application logs showing session limit errors or connection refused messages
- Test 2SFTP Connection Exhaustion via Python (Linux/macOS)
Expected signal: Process telemetry showing python3 spawning ~600 concurrent TCP connections to port 22; network visibility tools showing elevated socket counts; target host showing increased memory/thread usage for ServUDaemon.exe
- Test 3FTPS Connection Exhaustion via hping3 (Linux)
Expected signal: Network IDS/IPS alerts for SYN flood to port 990; firewall logs recording high packet rate from test source IP; Serv-U host showing elevated network interrupt handling load; Windows Performance Monitor showing ServUDaemon.exe handle/connection count spike
References (4)
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Get the full detection package for CVE-2026-28318 including response playbook, investigation guide, and atomic red team tests.