CAPEC-217 Detail

An adversary takes advantage of incorrectly configured SSL/TLS communications that enables access to data intended to be encrypted. The adversary may also use this type of attack to inject commands or other traffic into the encrypted stream to cause compromise of either the client or server.

Execution Flow

[Determine SSL/TLS Configuration] Determine the SSL/TLS configuration of either the server or client being targeted, preferably both. This is not a hard requirement, as the adversary can simply assume commonly exploitable configuration settings and indiscriminately attempt them.

• If the target is a webpage, some of the SSL/TLS configuration can be viewed through the browser's security information, such as the key sizes and cipher being used.

[Intercept Communication] Provide controlled access to the server by the client, by either providing a link for the client to click on, or by positioning one's self at a place on the network to intercept and control the flow of data between client and server, e.g. AiTM (adversary in the middle - CAPEC-94).

• Create a malicious webpage that looks identical to the target webpage, but routes client traffic to the server such that the adversary can observe the traffic and perform an adverary in the middle attack.
• If the adversary has access to the network that either the client or server is on, the can attempt to use a packet sniffer to perform an adversary in the middle attack.
• Install a packet sniffer through malware directly to a client device that can intercept SSL/TLS traffic and perform an adversary in the middle attack.

[Capture or Manipulate Sensitive Data] Once the adversary has the ability to intercept the secure communication, they exploit the incorrectly configured SSL to view the encrypted communication. The adversary can choose to just record the secure communication or manipulate the data to achieve a desired effect.

• Use known exploits for old SSL and TLS versions.
• Use known exploits for weak ciphers such as DES and RC4.

Prerequisites

Access to the client/server stream.

Skills Required

The adversary needs real-time access to network traffic in such a manner that the adversary can grab needed information from the SSL stream, possibly influence the decided-upon encryption method and options, and perform automated analysis to decipher encrypted material recovered. Tools exist to automate part of the tasks, but to successfully use these tools in an attack scenario requires detailed understanding of the underlying principles.

Resources Required

The adversary needs the ability to sniff traffic, and optionally be able to route said traffic to a system where the sniffing of traffic can take place, and act upon the recovered traffic in real time.

Mitigations

Do not use SSL, as all SSL versions have been broken and should not be used. If TLS is not an option for the client or server, consider setting timeouts on SSL sessions to extremely low values to lessen the potential impact.
Only use TLS version 1.2+, as versions 1.0 and 1.1 are insecure.
Configure TLS to use secure algorithms. The current recommendation is to use ECDH, ECDSA, AES256-GCM, and SHA384 for the most security.

Related Weaknesses

Submission

Modifications