PH_Rule_SIGMA_687
Enabled
Detects abusing Azure Browser SSO by requesting OAuth 2.0 refresh tokens for an Azure-AD-authenticated Windows user (i.e. the machine is joined to Azure AD and a user logs in with their Azure AD account) wanting to perform SSO authentication in the browser. An attacker can use this to authenticate to Azure AD in a browser as that user. . This rule is adapted from https://github.com/SigmaHQ/sigma/blob/master/rules/windows/image_load/image_load_abusing_azure_browser_sso.yml
3
Security
Defense Evasion
Defense Evasion consists of techniques that adversaries use to avoid detection throughout their compromise. Techniques used for defense evasion include uninstalling/disabling security software or obfuscating/encrypting data and scripts. Adversaries also leverage and abuse trusted processes to hide and masquerade their malware. Other tactics’ techniques are cross-listed here when those techniques include the added benefit of subverting defenses.
https://attack.mitre.org/tactics/TA0005T1574.002
Hijack Execution Flow: DLL Side-Loading
Adversaries may execute their own malicious payloads by hijacking the library manifest used to load DLLs. Adversaries may take advantage of vague references in the library manifest of a program by replacing a legitimate library with a malicious one, causing the operating system to load their malicious library when it is called for by the victim program. Adversaries likely use this technique as a means of masking actions they perform under a legitimate, trusted system or software process.
https://attack.mitre.org/techniques/T1574/002Server
Windows Sysmon via FortiSIEM Agent
Correlation
No remediation guidance specified
If the following pattern or patterns match an ingested event within the given time window in seconds, trigger an incident.
300 seconds
If the following defined pattern/s occur within a 300 second time window.
Filter
This is the named definition of the event query, this is important if multiple subpatterns are defined to distinguish them.
This is the query logic that matches incoming events
eventType="Win-Sysmon-7-Image-Loaded" AND (loadedProcName="C:\\Windows\\System32\\MicrosoftAccountTokenProvider.dll" AND ((procName NOT REGEXP "^C:\\Windows\\SysWOW64\\|^C:\\Windows\\System32\\" OR procName NOT REGEXP "\\BackgroundTaskHost\.exe$"))) AND ((procName NOT REGEXP "^C:\\Program Files \(x86\)\\Microsoft Visual Studio\\|^C:\\Program Files\\Microsoft Visual Studio\\" OR procName NOT REGEXP "\\IDE\\devenv\.exe$") AND (procName NOT IN ("C:\\Program Files (x86)\\Internet Explorer\\iexplore.exe","C:\\Program Files\\Internet Explorer\\iexplore.exe")) AND (procName NOT REGEXP "^C:\\Program Files \(x86\)\\Microsoft\\EdgeWebView\\Application\\" AND procName NOT REGEXP "\\WindowsApps\\MicrosoftEdge\.exe$" AND procName NOT IN ("C:\\Program Files (x86)\\Microsoft\\Edge\\Application\\msedge.exe","C:\\Program Files\\Microsoft\\Edge\\Application\\msedge.exe")) AND (procName NOT REGEXP "^C:\\Program Files \(x86\)\\Microsoft\\EdgeCore\\|^C:\\Program Files\\Microsoft\\EdgeCore\\" OR procName NOT REGEXP "\\msedge\.exe$|\\msedgewebview2\.exe$") AND (procName NOT REGEXP "\\AppData\\Local\\Microsoft\\OneDrive\\OneDrive\.exe$") AND (procName IS NOT NULL))
This defines how matching events are aggregated, only events with the same matching attribute values are grouped into one unique incident ID
hostName,loadedProcName,procName
This is most typically a numerical constraint that defines when the rule should trigger an incident
COUNT(*) >= 1
This section defines which fields in matching raw events should be mapped to the incident attributes in the resulting incident.
The available raw event attributes to map are limited to the group by attributes and the aggregate event constraint fields for each subpattern
hostName = Filter.hostName,
loadedProcName = Filter.loadedProcName,
procName = Filter.procName