Bishopfox Sliver vulnerabilities

Sliver C2 framework version 1.7.7 and earlier contains an unhandled panic vulnerability in the operator gRPC handler that allows an attacker controlling a compromised implant to crash the entire teamserver by returning a malformed or empty Download response. Attackers can send zero-length or 1-3 byte data payloads through a hostile implant session to trigger an out-of-bounds slice access in the vendored Binject library's BinaryMagic function, which propagates unrecovered through the operator gRPC interceptor chain and terminates the server process, affecting all connected operators.

Sliver is a command and control framework that uses a custom Wireguard netstack. Versions 1.7.3 and below contain a Remote OOM (Out-of-Memory) vulnerability in the Sliver C2 server's mTLS and WireGuard C2 transport layer. The socketReadEnvelope and socketWGReadEnvelope functions trust an attacker-controlled 4-byte length prefix to allocate memory, with ServerMaxMessageSize allowing single allocations of up to ~2 GiB. A compromised implant or an attacker with valid credentials can exploit this by sending fabricated length prefixes over concurrent yamux streams (up to 128 per connection), forcing the server to attempt allocating ~256 GiB of memory and triggering an OS OOM kill. This crashes the Sliver server, disrupts all active implant sessions, and may degrade or kill other processes sharing the same host. The same pattern also affects all implant-side readers, which have no upper-bound check at all. The issue was not fixed at the the time of publication.

Sliver is a command and control framework that uses a custom Wireguard netstack. In versions from 1.7.3 and prior, a vulnerability exists in the Sliver C2 server's Protobuf unmarshalling logic due to a systemic lack of nil-pointer validation. By extracting valid implant credentials and omitting nested fields in a signed message, an authenticated actor can trigger an unhandled runtime panic. Because the mTLS, WireGuard, and DNS transport layers lack the panic recovery middleware present in the HTTP transport, this results in a global process termination. While requiring post-authentication access (a captured implant), this flaw effectively acts as an infrastructure "kill-switch," instantly severing all active sessions across the entire fleet and requiring a manual server restart to restore operations. At time of publication, there are no publicly available patches.

Sliver is a command and control framework that uses a custom Wireguard netstack. Prior to 1.6.11, a path traversal in the website content subsystem lets an authenticated operator read arbitrary files on the Sliver server host. This is an authenticated path traversal / arbitrary file read issue, and it can expose credentials, configs, and keys. This vulnerability is fixed in 1.6.11.

Sliver is a command and control framework that uses a custom Wireguard netstack. In versions 1.5.43 and earlier, and in development version 1.6.0-dev, the netstack does not limit traffic between Wireguard clients. This allows clients to communicate with each other unrestrictedly, potentially enabling leaked or recovered keypairs to be used to attack operators or allowing port forwardings to be accessible from other implants.