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WeWorm – First 0-Click Worm Spreading Through WeChat Calls Across iOS and Android

Researchers demonstrated WeWorm, a zero-click worm exploiting a memory-corruption flaw in WeChat's VoIP stack to spread via calls across iOS and Android.

Security firm Calif published WeWorm, a proof-of-concept zero-click worm exploiting a memory-corruption bug in WeChat's VoIP stack to spread through voice calls on iOS and Android without the victim answering. The demo chained a Pixel 10a, an iPhone 17e, and a second Pixel 10a, compromising each device while the call was still ringing and giving full control of the WeChat account. The attacker must already be on the victim's friend list, but compromised contacts become the propagation layer across a platform with over 1.4 billion monthly users. Calif reported the bug to Tencent in July 2026, and Tencent has since mitigated it; full technical details are withheld for a later conference presentation.

Cyber Security News · 8d agoExploit / PoC

WeChat Worm Can Hijack Accounts Without Victims Answering Calls

Researchers demoed WeWorm, a zero-click WeChat worm hijacking accounts via incoming VoIP calls using a memory corruption flaw; Tencent patched it in August.

Researchers at Calif exploited a memory corruption bug in WeChat's VoIP system, taking over accounts through an incoming call even if the victim never answers or touches the phone. The attacker must already be a WeChat contact, but compromising a friend's account bypasses this, and chained calls spread the worm across three Android and iOS test phones in seconds. Tencent fixed the flaw in Android 8.0.77 and iOS 8.0.76 released in August, and researchers found no evidence of real-world exploitation. WeChat and Weixin reported 1.418 billion combined monthly active users at the end of 2025.

Security Affairs · 8d agoExploit / PoC

Teams calls are about to get a lot harder to fake

Microsoft will roll out Brand Impersonation Protection in Teams Calling from mid-May 2026, warning users about suspicious inbound VoIP calls impersonating trusted brands.

Microsoft Teams Calling is gaining Brand Impersonation Protection, which evaluates inbound VoIP calls from first-time external callers for signs of brand impersonation and displays warnings before users answer high-risk calls. The feature rolls out from mid-May 2026 with completion expected by late May 2026, is enabled by default, and requires no administrative action. Users can accept, block, or end flagged calls, and alerts may continue throughout a call if suspicious activity persists. Microsoft recommends preparing helpdesk teams and updating security awareness materials ahead of deployment.

Help Net Security · 12d agoTools