A more dramatic revelation of 2018—an outsider can secretly eavesdrop on your private end-to-end encrypted group chats on WhatsApp as well as also Signal messaging apps.
Considering protection against three types of attackers—malicious user, network attacker, as well as also malicious server—an end-to-end encryption protocol plays a vital role in securing instant messaging services.
The primary purpose of having end-to-end encryption is usually to stop trusting the intermediate servers in such a way that will no one, not even the company or the server that will transmits the data, can decrypt your messages or abuse its centralized position to manipulate the service.
In order words—assuming the worst-case scenario—a corrupt company employee should not be able to eavesdrop on the end-to-end encrypted communication by any mean.
However, so far even the well-known end-to-end encrypted messaging services, like WhatsApp, Threema as well as also Signal, have not entirely achieved zero-knowledge system.
Researchers through Ruhr-Universität Bochum (RUB) in Germany found that will anyone who controls WhatsApp/Signal servers can covertly add completely new members to any private group, allowing them to spy on group conversations, even without the permission of the administrator.
As described by the researchers, from the pairwise communication (when only two users communicate with each some other) server plays a limited role, although in case of multi-user chats (group chat where encrypted messages are broadcasted to many users), the role of servers increases to manage the entire process.
that will’s where the issue resides, i.e. trusting the company’s servers to manage group members (who eventually have full access to the group conversation) as well as also their actions.
As explained from the newly published RUB paper, titled “More is usually Less: On the End-to-End Security of Group Chats in Signal, WhatsApp, as well as also Threema,” since both Signal as well as also WhatsApp fail to properly authenticate that will who is usually adding a completely new member to the group, the idea is usually possible for an unauthorized person—not a group administrator or even a member of the group—to add someone to the group chat.
What’s more? If you are wondering that will adding a completely new member to the group will show a visual notification to some other members, the idea is usually not the case.
According to the researchers, a compromised admin or rogue employee with access to the server could manipulate (or block) the group management messages that will are supposed to alert group members of a completely new member.
“The described weaknesses enable attacker A, who controls the WhatsApp server or can break the transport layer security, to take full control over a group. Entering the group, however, leaves traces since that will operation is usually listed from the graphical user interface. The WhatsApp server can therefore use the fact that will the idea can stealthily reorder as well as also drop messages from the group,” the paper reads.
“Thereby the idea can cache sent messages to the group, read their content first as well as also decide in which order they are delivered to the members. Additionally, the WhatsApp server can forward these messages to the members individually such that will a subtly chosen combination of messages can help the idea to cover the traces.”
WhatsApp has acknowledged the issue, although argued that will if any completely new member is usually added to a group, let’s say by anyone, some other group members will get notified for sure.
“We’ve looked at that will issue carefully. Existing members are notified when completely new people are added to a WhatsApp group. We built WhatsApp so group messages cannot be sent to a hidden user,” a WhatsApp spokesperson told Wired.
“The privacy as well as also security of our users is usually incredibly important to WhatsApp. the idea’s why we collect very little information as well as also all messages sent on WhatsApp are end-to-end encrypted.”
although if you are not part of a group with very selected members, I’m sure many of you would certainly relatively ignore such notifications easily.
Researchers also advised companies to fix the issue just by adding an authentication mechanism to make sure that will the “signed” group management messages come through the group administrator only.
However, that will attack is usually not easy (exception—services under legal pressure) to execute, so users should not be worried about the idea.