Cisco has warned users of its Webex enterprise conferencing system about an automated online attack technique that would allow anyone to join a meeting and listen in on what should be a private conversation.
The company has published an 'informational advisory' about a Cisco Webex Meetings 'enumeration attack', referring to a method where an attacker can essentially guess the numerical identifier that allows intended participants to join a Webex meeting.
The attack method was identified by Cequence Security, which warned Cisco that one of its Webex application protocol interface (API) calls allows an attacker to enumerate meeting numbers for access to ongoing or future meetings.
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The impact on the user is that an attacker could tell when a certain meeting number is in use and whether the meeting requires a password to join.
That could be bad news for anyone expecting a conversation to be private. However, Cisco hasn't released a patch to address the issue, suggesting it's not a vulnerability but a configuration issue. However, it has offered recommendations to ensure attackers can abuse this API.
Cequence Security, a US company focusing on application security, has detailed what it calls the 'Prying-Eye vulnerability', which also affects video collaboration company Zoom.
Zoom had its IPO in April and in July caused a stir after it appeared to ignore a legitimate bug report that its web server exposed Mac users to remote attacks.
"The Prying-Eye vulnerability is an example of an enumeration attack that targets web-conferencing APIs with a bot that cycles through (enumerates) and discovers valid numeric meeting IDs," Cequence explained in a blogpost.
"If the common user practice of disabling security functionality or not assigning a password is followed, then the bad actor would be able to view or listen to an active meeting."
To make it easier for participants to join, those setting up a meeting often don't require them to use a password. But if companies know a conversation could involve the exchange of sensitive information, it could be wise for them to protect the meeting with a password.
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In Cisco's case, Webex Meetings uses a nine-digit identifier that participants can use to join a meeting from smartphones and desktops. It notes the potential security issue mostly affects meetings that aren't password-protected.
"If the attacker was to join the meeting using this information, they would still be listed as a participant and could be expelled by the host," Cisco says.
"For password-protected meetings, the attacker could recover the meeting number, but would not be able to uncover the meeting title, schedule or host name, or join the meeting."
The company notes that the default configuration makes it mandatory to use a password when users are setting up a meeting.
Webex also offers a default, randomly generated password when setting up a meeting in sites that do not mandate password protection. Customers can ditch the randomly generated one and share an easier, user-created password or disable password protection if the site allows it.