The Torbutton extension installed in amnesia being incompatible with Icedove (Thunderbird), the real IP address of the computer is disclosed to the SMTP relay that is used to send email.

Impact

When using Icedove to send email, the computer's real IP address is disclosed to the SMTP relay, that usually writes it down to a Received: header inside outgoing email. This private information is therefore disclosed to:

  • the SMTP relay's administrators;
  • anyone who is able to read such a sent email, including: anyone the email is sent to, various network and email servers administrators.

When using a NAT-ed Internet connection, the disclosed IP is a local network one (e.g. 192.168.1.42), which usually does not reveal too much. On the other hand, when connecting directly to the Internet, e.g. using a PPP or DSL modem and no router, the disclosed IP truly reveals the location of the amnesia user.

Solution

Upgrade to amnesia 0.4.1, that ships with Claws Mail instead of Icedove, and set the following preferences in ~/.claws-mail/accountrc for every account:

    set_domain=1
    domain=localhost

Mitigation

Best is to avoid using Icedove (Thunderbird) in amnesia until fixed images are released. If not possible:

  • Use amnesia behind a NAT-ed Internet connection, inside a LAN that uses widespread IP addresses.
  • Use a trustworthy, privacy-friendly SMTP relay that does not write down the client's IP address anywhere, especially in email headers.

Note that using GnuPG does not fix this problem at all: GnuPG only encrypts the email body, the email headers being always kept in clear.

Affected versions

Any amnesia release until, and including, 0.3. amnesia 0.4 is not affected.