One signature error turned the public Tor descriptor into key recovery material that manages the site’s address. Searchlight Cyber has revealed a GoBalance vulnerability that allows you to calculate the secret key of the .onion service without any access to the server, and then intercept the familiar address and redirect visitors to someone else's resource.
GoBalance is a Go version of OnionBalance that distributes a single .onion address between multiple servers. This mechanism increases the availability of hidden services during overload and attacks. It is the fight against DDoS that remains one of the difficult tasks for onion services, where conventional IP filtering is ineffective, so operators apply balancers.
An error occurs when working with a private Tor key format Ed25519. The key contains 64 bytes, but GoBalance only transmits the signature functions to the first 32 bytes. The second half is necessary for the formation of a secret meaning on which the uniqueness of the signature depends. After truncation, the value becomes predictable, and one public descriptor is enough to calculate a long-term master key.
The resulting key does not open the database and does not give direct access to the servers. But the owner of the key can publish correctly signed descriptors for the same .onion address and send visitors to the controlled node. This substitution creates conditions for phishing, interception of credentials and showing a modified copy of the site without hacking the original infrastructure.
The real incident affected the Dread forum. From 5 to 7 October, two of his .onion addresses intercepted and redirected to the competing Conclave resource. The first case of Dread administrators was associated with the erroneous publication of a private key, but the seizure of the reserve address later pointed to a separate problem in GoBalance. Searchlight Cyber considers the vulnerability the most likely explanation for the second episode.
Dread after the incident moved to a new address and recommended that users change passwords. The Omega site also disabled the old address and reported on the GoBalance-related issue. The exact number of services affected is unknown. Tor itself and the original OnionBalance, according to Searchlight Cyber, have no vulnerabilities, and the risk concerns configurations with a master key in Tor format.
There is no official correction and CVE ID on October 9. The independent developer has published a patch and demonstration code to restore the test key from one descriptor, but the release is not considered official. A simple update is not enough for the already disclosed key, so the affected services will have to release a new .onion address.
GoBalance is a Go version of OnionBalance that distributes a single .onion address between multiple servers. This mechanism increases the availability of hidden services during overload and attacks. It is the fight against DDoS that remains one of the difficult tasks for onion services, where conventional IP filtering is ineffective, so operators apply balancers.
An error occurs when working with a private Tor key format Ed25519. The key contains 64 bytes, but GoBalance only transmits the signature functions to the first 32 bytes. The second half is necessary for the formation of a secret meaning on which the uniqueness of the signature depends. After truncation, the value becomes predictable, and one public descriptor is enough to calculate a long-term master key.
The resulting key does not open the database and does not give direct access to the servers. But the owner of the key can publish correctly signed descriptors for the same .onion address and send visitors to the controlled node. This substitution creates conditions for phishing, interception of credentials and showing a modified copy of the site without hacking the original infrastructure.
The real incident affected the Dread forum. From 5 to 7 October, two of his .onion addresses intercepted and redirected to the competing Conclave resource. The first case of Dread administrators was associated with the erroneous publication of a private key, but the seizure of the reserve address later pointed to a separate problem in GoBalance. Searchlight Cyber considers the vulnerability the most likely explanation for the second episode.
Dread after the incident moved to a new address and recommended that users change passwords. The Omega site also disabled the old address and reported on the GoBalance-related issue. The exact number of services affected is unknown. Tor itself and the original OnionBalance, according to Searchlight Cyber, have no vulnerabilities, and the risk concerns configurations with a master key in Tor format.
There is no official correction and CVE ID on October 9. The independent developer has published a patch and demonstration code to restore the test key from one descriptor, but the release is not considered official. A simple update is not enough for the already disclosed key, so the affected services will have to release a new .onion address.
