Detect CVE-2026-48558 — SimpleHelp Authentication Bypass (CWE-347) in Elastic Security
Detects exploitation of CVE-2026-48558, an authentication bypass vulnerability in SimpleHelp remote support software caused by improper verification of cryptographic signatures (CWE-347). This KEV-listed vulnerability allows unauthenticated attackers to bypass authentication controls. SimpleHelp is commonly used by MSPs and IT support teams, making it a high-value target for initial access and lateral movement.
MITRE ATT&CK
Elastic Detection Query
sequence by source.ip with maxspan=5m
[network where destination.port in (80, 443, 5850, 5900)
and http.request.method in ("GET", "POST")
and url.path : ("/admin*", "/operator*", "/technician*", "/api/admin*")]
[network where destination.port in (80, 443, 5850, 5900)
and http.response.status_code in (200, 302)
and url.path : ("/admin*", "/operator*", "/technician*")
and not (user.name != null and user.name != "-")]EQL sequence detection correlating an unauthenticated request to a SimpleHelp privileged endpoint followed by a successful HTTP response, indicating authentication bypass exploitation of CVE-2026-48558.
Data Sources
Required Tables
False Positives & Tuning
- Misconfigured SimpleHelp instances that serve admin content without authentication by design
- Internal network scanners touching SimpleHelp endpoints as part of asset discovery
- Proxy or WAF log forwarding that strips authentication headers before indexing
- Automated backup or configuration management tools accessing SimpleHelp APIs
Other platforms for CVE-2026-48558
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 1CVE-2026-48558 — Unauthenticated Admin Endpoint Access Probe
Expected signal: Web server access logs will show GET requests to /admin, /operator, /technician, and /api/admin from the test host IP. Network flow data will show connections from test host to SimpleHelp port. IDS/IPS may generate HTTP policy violation alerts.
- Test 2CVE-2026-48558 — Signature Verification Bypass via Malformed Token
Expected signal: Application logs should show authentication attempts with malformed tokens. Web server logs will record requests with Authorization headers containing invalid credentials. Endpoint detection may flag the curl process making connections to internal services.
- Test 3CVE-2026-48558 — Post-Bypass Operator Account Enumeration
Expected signal: Multiple sequential API requests to /api/admin/* paths from single source IP within short timeframe. Application logs show operator/technician/config endpoint access. UEBA tools may flag unusual API access patterns if baselining is in place.
References (4)
- https://simple-help.com/security/simplehelp-security-update-2026-05
- https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk
- https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk
- https://nvd.nist.gov/vuln/detail/CVE-2026-48558
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