https://bugs.kde.org/show_bug.cgi?id=391667
Jan Kundrát <j...@kde.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Summary|Security bug |EFAIL: leak of the
| |plaintext of encrypted
| |emails
--- Comment #7 from Jan Kundrát <j...@kde.org> ---
This appears to have gone public now. Technical details are available in the
paper [1]. Trojita is listed as vulnerable (page 20) for two classes of
exfiltration scenarios:
- I3: "CRL requests to a fixed CA URL are performed for valid/trusted S/MIME
signed emails"
- H3, which is about the DNS prefetch control: <meta
http-equiv="x-dns-prefetch-control" content="on"><a href="http://efail.de";></a>
The I3 is outside of control of Trojita. We are using the libgpgme library for
all crypto operations, including the CRL handling. We do not issue any
cert/CRL/key/... requests directly. Once gpgme is fixed, Trojita will be fixed,
too.
The H3 has been reported in bug 390452, and that's upstream
https://bugreports.qt.io/browse/QTBUG-67068 . Our code has always included
explicit disabling of the DNS prefetch for QtWebKit; unfortunately, due to a
bug in upstream qtwebkit, this does not take any effect. We *could* try to
mitigate the problem by mangling the HTML code, trying to insert an explicit
<meta> element which disables this DNS prefetch. However, these attempts tend
to be error-prone because there are many ways on how to re-enable various
features in HTML renderers.
There are other attacks as well. The user is still presented with a button to
enable remote content when displaying encrypted e-mails. That should probably
be disabled in order to make sure that the plaintext content won't leak by
accident.
[1] https://efail.de/efail-attack-paper.pdf
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