CVE-2024-38197: Microsoft Teams iOS Spoofing Vulnerability

CVE-2024-38197 Overview

CVE-2024-38197 is a spoofing vulnerability in Microsoft Teams for iOS. Microsoft disclosed the flaw in August 2024. The issue is tracked under [CWE-451] (User Interface Misrepresentation of Critical Information). An unauthenticated attacker can abuse the mobile client to present misleading information to targeted users over the network.

The vulnerability affects the iOS build of Microsoft Teams and does not require user interaction or elevated privileges. Successful exploitation compromises confidentiality and integrity at a limited scope, but does not impact availability. The EPSS score is 16.084% with a percentile of 96.53, indicating higher-than-average predicted exploitation likelihood relative to the broader CVE population.

Critical Impact
An unauthenticated remote attacker can spoof interface elements in Microsoft Teams for iOS, enabling social engineering against enterprise users on mobile devices.

Affected Products

Microsoft Teams for iOS (iPhone OS platform)
Mobile Teams clients prior to the Microsoft security update addressing CVE-2024-38197
Enterprise deployments relying on Teams mobile for collaboration and authentication flows

Discovery Timeline

2024-08-13 - CVE-2024-38197 published to the National Vulnerability Database
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2024-38197

Vulnerability Analysis

CVE-2024-38197 is a user interface misrepresentation issue classified under [CWE-451]. The Microsoft Teams iOS client fails to correctly convey the identity or trust context of certain interface elements to the user. An attacker leveraging this weakness can craft content that appears to originate from a trusted party inside the Teams app.

Because Teams is widely used for corporate messaging, meetings, and file exchange, spoofed elements can be weaponized in phishing and social engineering campaigns. Attackers exploiting spoofing flaws typically pair them with credential harvesting, malicious link delivery, or fraudulent instructions that impersonate executives or IT staff. The mobile form factor amplifies the risk because users have less screen real estate to inspect sender identity and message context.

Root Cause

The root cause lies in how the Teams iOS client renders identity or security-relevant metadata within chat, notification, or meeting surfaces. Insufficient validation or presentation logic allows attacker-controlled data to override or mimic trusted UI indicators. Microsoft has not published low-level implementation detail beyond the advisory.

Attack Vector

The attack vector is network-based and requires no authentication or user interaction beyond the victim viewing crafted content in Teams. An attacker sends specially formatted messages, invites, or embedded content to a Teams user on iOS. The client renders the malicious payload in a way that misrepresents its origin or trust level, deceiving the recipient. See the Microsoft CVE-2024-38197 Advisory for vendor guidance.

Detection Methods for CVE-2024-38197

Indicators of Compromise

Inbound Teams messages, meeting invites, or federated chat requests from unexpected external tenants that impersonate internal identities
User reports of Teams notifications or chat threads that display mismatched sender names, avatars, or organization labels
Unusual click-through activity from Teams mobile clients to newly registered or low-reputation external domains

Detection Strategies

Correlate Microsoft 365 audit logs, Teams messaging telemetry, and Defender for Office 365 alerts to identify federated or guest-originated messages targeting multiple internal users
Hunt for external-to-internal Teams communications that reference finance, credentials, MFA prompts, or executive impersonation themes
Monitor mobile device management (MDM) logs for Teams iOS versions that predate the Microsoft security update

Monitoring Recommendations

Enable and review Teams external access and federation policies, alerting on new or anonymous external senders
Ingest Microsoft 365 audit and Teams activity logs into a centralized analytics platform for correlation with endpoint and identity telemetry
Track Teams iOS client versions across the fleet and alert on devices running vulnerable builds

How to Mitigate CVE-2024-38197

Immediate Actions Required

Update Microsoft Teams for iOS to the version identified in the Microsoft CVE-2024-38197 Advisory through the Apple App Store or MDM-managed app deployment
Enforce automatic app updates for Teams through your mobile device management platform
Notify users of the spoofing risk and reinforce verification procedures for sensitive requests received via Teams

Patch Information

Microsoft has released an updated Microsoft Teams for iOS build that addresses CVE-2024-38197. Refer to the Microsoft CVE-2024-38197 Advisory for the fixed version and deployment guidance. Organizations using Intune or other MDM solutions should push the updated app package to all managed iOS devices.

Workarounds

Restrict Teams external access and federation to explicitly allowed partner tenants until all mobile clients are patched
Disable anonymous meeting join and guest chat where business requirements allow
Train users to verify unexpected Teams requests through a secondary channel, especially those involving credentials, payments, or MFA approval

bash

# Example: Restrict Teams external access via PowerShell (Microsoft Teams module)
Set-CsTenantFederationConfiguration -AllowFederatedUsers $true -AllowedDomains @{Add="partner.example.com"}
Set-CsTenantFederationConfiguration -AllowTeamsConsumer $false
Set-CsTeamsMeetingPolicy -Identity Global -AllowAnonymousUsersToJoinMeeting $false