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Unlock with Pro - from £29/user/moDetect Pheditor Hardcoded Default Administrator Credential Exploitation (CVE-2026-55579) in Google Chronicle
Detects authentication and post-authentication activity consistent with exploitation of CVE-2026-55579, a hardcoded default password ('admin') in Pheditor (composer package pheditor/pheditor) versions >= 2.0.1 and < 2.0.6. The vulnerability (CWE-798) allows any unauthenticated attacker with network access to the application to log in using the well-known default credential and achieve full application compromise, since the application does not force a password change on first login. Detection logic focuses on successful logins using the literal 'admin' credential pair, rapid login attempts against the default account, and suspicious follow-on activity (admin panel access, plugin/file upload, config changes) shortly after such a login.
MITRE ATT&CK
YARA-L Detection Query
rule pheditor_default_admin_login {
meta:
author = "detection-engineering"
description = "Detects login to Pheditor using hardcoded default admin credential (CVE-2026-55579)"
severity = "Critical"
reference = "https://github.com/pheditor/pheditor/security/advisories/GHSA-p4h7-p9rj-2pq2"
events:
$login.metadata.event_type = "USER_LOGIN"
$login.target.user.userid = "admin"
$login.network.http.method = "POST"
$login.target.url = /login/
condition:
$login
}YARA-L rule that flags USER_LOGIN events targeting Pheditor's login endpoint with the userid 'admin', consistent with exploitation of the hardcoded default credential.
Data Sources
Required Tables
False Positives & Tuning
- Legitimate administrators who have not rotated the default password
- Authorized red team/pentest logins
- Automated compliance scanners checking for default credentials
Other platforms for CVE-2026-55579
Testing Methodology
Validate this detection against 4 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 1Simulate Default Credential Login Attempt
Expected signal: HTTP POST request to /login containing username=admin in the request body, followed by a 200/302 response and session cookie issuance.
- Test 2Simulate Post-Login Admin Panel Access
Expected signal: Authenticated HTTP GET request to /admin/dashboard using the session cookie obtained from the default-credential login.
- Test 3Simulate Malicious Plugin Upload via Compromised Admin Session
Expected signal: HTTP POST multipart file upload request to the plugin upload endpoint from an authenticated 'admin' session, followed by creation of a new file in the Pheditor plugins directory.
- Test 4Windows-Based Simulated Login Attempt via PowerShell
Expected signal: Outbound HTTP POST request from the test host to the Pheditor login endpoint containing the default credential pair, logged in network/proxy telemetry.
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