Detect SolarWinds Serv-U Uncontrolled Resource Consumption (CVE-2026-28318) in IBM QRadar
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
QRadar Detection Query
SELECT
sourceip,
destinationip,
destinationport,
COUNT(*) AS connection_count,
SUM("bytessentpacketcount") AS total_bytes,
MIN(starttime) AS window_start,
MAX(starttime) AS window_end
FROM events
WHERE
destinationport IN (21, 22, 990, 989, 443, 80)
AND (logsourcename ILIKE '%serv-u%' OR logsourcename ILIKE '%solarwinds%' OR destinationport IN (21, 990, 989))
AND starttime > NOW() - 3600000
GROUP BY
sourceip,
destinationip,
destinationport,
DATEFORMAT(starttime, 'yyyy-MM-dd HH:mm', 300000)
HAVING connection_count > 500
ORDER BY connection_count DESC
LAST 60 MINUTESQRadar AQL query aggregating connection events to Serv-U service ports, flagging source IPs generating more than 500 connections within 5-minute intervals as potential resource exhaustion attacks.
Data Sources
Required Tables
False Positives & Tuning
- Batch processing jobs that open large numbers of FTP sessions for data migration
- Network performance testing generating artificial traffic spikes
- Legitimate customers with high-volume file transfer requirements
- Internal monitoring agents polling Serv-U service health frequently
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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