Zenly Bugs Exposed Users to Data Loss and Account Takeover

Security experts have revealed two vulnerabilities they located in a well-known social app which could permit account takeover (ATO) or client data reduction.

The now-patched issues were being provided a medium CVSS rating. They show up in Zenly, a smartphone application that makes it possible for buyers to see where pals and loved ones are on a map.

The initially bug exposes users’ phone numbers and could therefore be applied to craft plausible vishing attacks, in accordance to scientists at Checkmarx.

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“When submitting a close friend request to a consumer, Zenly will allow obtain to their phone variety irrespective of irrespective of whether the pal ask for is recognized or not. To acquire this details, a destructive actor only demands to know their username,” they explained.

“While acquiring a username could be a difficult job by itself, it is designed much easier by the point Zenly also exposes an exhaustive checklist of close friends of a person. This signifies that, for obtaining the phone range of a user, a destructive actor does not will need to know their username at the get started, but is ready to follow a chain of close friends until one of them has the target in their close friends listing.”

Checkmarx warned that the bug could be exploited to goal CEOs or senior final decision makers in companies who may well be working with the application, through other people in the group.

The second ATO vulnerability stems from the way the Zenly API handles session authentication.

It typically phone calls a “/SessionCreate” endpoint with the phone amount of the consumer, which then makes a session token, and sends an SMS verification code to the person. It then calls the “/SessionVerify” endpoint with equally the session token and the verification code acquired by SMS, in order to log the consumer in.

“An attacker can just take in excess of a person account by abusing the /SessionCreate endpoint, which will persistently return the same session token (whilst not nevertheless legitimate) for the very same user. At the time the legitimate user validates the SMS code for that session token, the session will grow to be valid for both the genuine consumer and the attacker,” Checkmarx spelled out.

“The major point of this issue is that the attacker needs to get hold of a session token ahead of the legitimate person calls the /SessionVerify endpoint. This can be done possibly ahead of or just after the legit consumer phone calls the /SessionCreate endpoint.”

Nevertheless, this isn’t always straightforward to reach, that’s why the CVSS score of 4.7. It would call for the attacker to know the victim’s cell and have understanding of when the victim will login, signal up, sign-up a new device or go through the authentication flow for other explanations.

Checkmarx thanked Zenly for its professionalism, cooperation and prompt possession in operating to resolve the issues.