Title: Tor Cryptographic Handshake Remote Information Disclosure Vulnerability
Severity: HIGH
Description:
Tor is an implementation of second generation Onion Routing, a connection-oriented anonymizing communication service. Tor utilizes the DH (Diffie-Hellman) key exchange protocol to create ephemeral keys for encryption when communicating with servers in the Tor network. The Tor network uses random paths through the Tor routers to obscure the origin, destination, and contents of TCP based network communication.
Tor is susceptible to a remote information disclosure vulnerability. This issue is due to a flaw in the implementation of the Diffie-Hellman key exchange protocol.
Specifically, certain values used during the Diffie-Hellman key exchange protocol are insecure, and when used, lead to the ability of attackers to access the negotiated encryption keys.
If the first Tor router that a vulnerable client communicates with is malicious, it can force the use of the insecure values in the DH key exchange protocol. The malicious router can then gain access to, or spoof the contents of all further communication that the unsuspecting client computer forwards through the Tor network.
This vulnerability allows attackers to gain access to the negotiated keys used to encrypt the communications between Tor servers and clients. This allows attackers to read or modify all the traffic that is sent from the targeted user over the Tor network. The anonymity, confidentiality, and integrity guarantees of the network are lost through the exploitation of this issue.
Affected Products:
- Gentoo Linux
- Tor Tor 0.1.0 .0.10
- Tor Tor 0.1.0 .0.11
- Tor Tor 0.1.0 .0.12
- Tor Tor 0.1.0 .0.13
- Tor Tor 0.1.1 .1-alpha
- Tor Tor 0.1.1 .2-alpha
- Tor Tor 0.1.1 .3-alpha
- Tor Tor 0.1.1 .4-alpha
References:
Juniper Networks provides this content via a wide variety of sources and production methods. If notified of errors or omissions in the content of this page, Juniper Networks, at its discretion, will modify or remove the page or leave the content as is, depending on various factors including but not limited to the reputation and authority of the party providing the notification. Please use the contact information displayed elsewhere on this page to report any errors or omissions regarding the content on this page.
