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diff --git a/docs/server-server/security-threat-model.rst b/docs/server-server/security-threat-model.rst new file mode 100644 index 0000000000..cf0430e43d --- /dev/null +++ b/docs/server-server/security-threat-model.rst @@ -0,0 +1,141 @@ +Overview +======== + +Scope +----- + +This document considers threats specific to the server to server federation +synapse protocol. + + +Attacker +-------- + +It is assumed that the attacker can see and manipulate all network traffic +between any of the servers and may be in control of one or more homeservers +participating in the federation protocol. + +Threat Model +============ + +Denial of Service +----------------- + +The attacker could attempt to prevent delivery of messages to or from the +victim in order to: + + * Disrupt service or marketing campaign of a commercial competitor. + * Censor a discussion or censor a participant in a discussion. + * Perform general vandalism. + +Threat: Resource Exhaustion +~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +An attacker could cause the victims server to exhaust a particular resource +(e.g. open TCP connections, CPU, memory, disk storage) + +Threat: Unrecoverable Consistency Violations +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +An attacker could send messages which created an unrecoverable "split-brain" +state in the cluster such that the victim's servers could no longer dervive a +consistent view of the chatroom state. + +Threat: Bad History +~~~~~~~~~~~~~~~~~~~ + +An attacker could convince the victim to accept invalid messages which the +victim would then include in their view of the chatroom history. Other servers +in the chatroom would reject the invalid messages and potentially reject the +victims messages as well since they depended on the invalid messages. + +Threat: Block Network Traffic +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +An attacker could try to firewall traffic between the victim's server and some +or all of the other servers in the chatroom. + +Threat: High Volume of Messages +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +An attacker could send large volumes of messages to a chatroom with the victim +making the chatroom unusable. + +Threat: Banning users without necessary authorisation +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +An attacker could attempt to ban a user from a chatroom with the necessary +authorisation. + +Spoofing +-------- + +An attacker could try to send a message claiming to be from the victim without +the victim having sent the message in order to: + + * Impersonate the victim while performing illict activity. + * Obtain privileges of the victim. + +Threat: Altering Message Contents +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +An attacker could try to alter the contents of an existing message from the +victim. + +Threat: Fake Message "origin" Field +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +An attacker could try to send a new message purporting to be from the victim +with a phony "origin" field. + +Spamming +-------- + +The attacker could try to send a high volume of solicicted or unsolicted +messages to the victim in order to: + + * Find victims for scams. + * Market unwanted products. + +Threat: Unsoliticted Messages +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +An attacker could try to send messages to victims who do not wish to receive +them. + +Threat: Abusive Messages +~~~~~~~~~~~~~~~~~~~~~~~~ + +An attacker could send abusive or threatening messages to the victim + +Spying +------ + +The attacker could try to access message contents or metadata for messages sent +by the victim or to the victim that were not intended to reach the attacker in +order to: + + * Gain sensitive personal or commercial information. + * Impersonate the victim using credentials contained in the messages. + (e.g. password reset messages) + * Discover who the victim was talking to and when. + +Threat: Disclosure during Transmission +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +An attacker could try to expose the message contents or metadata during +transmission between the servers. + +Threat: Disclosure to Servers Outside Chatroom +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +An attacker could try to convince servers within a chatroom to send messages to +a server it controls that was not authorised to be within the chatroom. + +Threat: Disclosure to Servers Within Chatroom +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +An attacker could take control of a server within a chatroom to expose message +contents or metadata for messages in that room. + + |