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Arnold Chan

@slaz
Trusted contributorCompletionist
2 followers2,099 downloads4,366 copies51 likes26,035 views

7,555 detections

Detects patterns associated with the TeamFiltration backdoor module, specifically unauthorized OneDrive/SharePoint file modifications occurring shortly after an authentication from a previously unseen device/IP. The rule flags file changes (modifications, deletions, or renames) involving potential executable or script extensions, or those performed by the OneDrive SyncEngine app from a new source.
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Arnold Chan@slaz
Defender - KQL
1 month ago
101
Detects high-volume account enumeration activity associated with the TeamFiltration tool, characterized by the use of legacy Microsoft Teams desktop client User-Agent strings (specific versions of Teams, Electron, and Chrome) within a short time window.
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Arnold Chan@slaz
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Detection & Hunting Community
1 month ago
101
Detects high-volume account enumeration activity associated with the TeamFiltration tool, characterized by the use of legacy Microsoft Teams desktop client User-Agent strings (specific versions of Teams, Electron, and Chrome) within a short time window.
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Arnold Chan@slaz
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Detections.ai Community
1 month ago
001
Detects the 'auto-exfil' pattern associated with the TeamFiltration tool. The rule identifies a sequence of SharePoint Online file access immediately followed by a Microsoft Graph token request from the SharePoint Online Web Client Extensibility app. To reduce noise, it mandates a very short time delta between events (<= 60 seconds) combined with either the use of an IP address/ASN not previously seen for the account in the last 14 days, or a preceding failed sign-in attempt for the account.
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Arnold Chan@slaz
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Hunters
1 month ago
001
Detects the 'auto-exfil' pattern associated with the TeamFiltration tool. The rule identifies a sequence of SharePoint Online file access immediately followed by a Microsoft Graph token request from the SharePoint Online Web Client Extensibility app. To reduce noise, it mandates a very short time delta between events (<= 60 seconds) combined with either the use of an IP address/ASN not previously seen for the account in the last 14 days, or a preceding failed sign-in attempt for the account.
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Arnold Chan@slaz
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Midnight Slayer
1 month ago
001
Detects a suspected account compromise sequence where an account first authenticates to a Microsoft Teams application from infrastructure associated with TeamFiltration (e.g., specific AWS ranges), followed by a rapid (within 2 minutes) authentication to a VPN or SAML service provider from a different IP address, indicative of an account pivot.
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Arnold Chan@slaz
Defender - KQL
1 month ago
001
Detects a suspected account compromise sequence where an account first authenticates to a Microsoft Teams application from infrastructure associated with TeamFiltration (e.g., specific AWS ranges), followed by a rapid (within 2 minutes) authentication to a VPN or SAML service provider from a different IP address, indicative of an account pivot.
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Arnold Chan@slaz
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Detection & Hunting Community
1 month ago
001
Detects a suspected account takeover pattern where an Azure AD account logs into the Azure Portal shortly after experiencing failed authentication attempts from the same IP address. The detection correlates password spraying or VPN probing activity (multiple failed logins against different users from a single IP) with subsequent successful or near-successful logins (MFA enrollment interrupts) on the Azure Portal, signaling potential post-compromise activity.
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Arnold Chan@slaz
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Detections.ai Community
1 month ago
101
Detects the TeamFiltration/UNK_CondorFiltration spray signature: a large
number of distinct target UserPrincipalNames within a single tenant, each
receiving only a handful of sign-in attempts, spread across many distinct
AWS EC2-hosted source IPs/regions within a short time window. Individual
sign-ins from AWS-hosted IP ranges (VPN gateways, corporate cloud proxies,
remote contractors) are not flagged on their own; the rule requires both
the account-fanout and the IP-rotation dimensions to co-occur for the same
tenant in the same window.
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Arnold Chan@slaz
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Midnight Slayer
1 month ago
101
Detects the TeamFiltration/UNK_CondorFiltration spray signature: a large
number of distinct target UserPrincipalNames within a single tenant, each
receiving only a handful of sign-in attempts, spread across many distinct
AWS EC2-hosted source IPs/regions within a short time window. Individual
sign-ins from AWS-hosted IP ranges (VPN gateways, corporate cloud proxies,
remote contractors) are not flagged on their own; the rule requires both
the account-fanout and the IP-rotation dimensions to co-occur for the same
tenant in the same window.
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Arnold Chan@slaz
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Hunters
1 month ago
001
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