Vulnerability identifier: #VU49847

Vulnerability risk: Low

CVSSv3.1: 3.8 [CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N/E:U/RL:O/RC:C]

CVE-ID: N/A

CWE-ID: CWE-345

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Signal
Mobile applications / Apps for mobile phones

Vendor:

Description

The vulnerability allows a remote attacker to gain access to sensitive information.

The vulnerability exists due to the way the mobile application implements WebRTC features for voice and video communications. A remote attacker can send specially crafted SDP messages to the affected device while the victim is trying to make a voice or video call and intercept video and audio fragments from the victim's phone before the call is accepted by the callee.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

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External links
http://www.bleepingcomputer.com/news/security/bugs-in-signal-facebook-google-chat-apps-let-attackers-spy-on-users/
http://googleprojectzero.blogspot.com/2021/01/the-state-of-state-machines.html

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.