Calling CGI::FormBuilder::field with a name argument in list context
returns zero or more user-specified values of the named field, even
if that field was not declared as supporting multiple values.
Passing the result of field as a function parameter counts as list
context. This is the same bad behaviour that is now discouraged
for CGI::param.
In this case we pass the multiple values to CGI::Session::param.
That accessor has six possible calling conventions, of which four are
documented. If an attacker passes (2*n + 1) values for the 'name'
field, for example name=a&name=b&name=c, we end up in one of the
undocumented calling conventions for param:
# equivalent to: (name => 'a', b => 'c')
$session->param('name', 'a', 'b', 'c')
and the 'b' session parameter is unexpectedly set to an
attacker-specified value.
In particular, if an attacker "bob" specifies
name=bob&name=name&name=alice, then authentication is carried out
for "bob" but the CGI::Session ends up containing {name => 'alice'},
an authentication bypass vulnerability.
This vulnerability is tracked as OVE-20170111-0001.
(cherry picked from commit e909eb93f4530a175d622360a8433e833ecf0254)
The Debian security tracker gets timely updates, whereas the official
CVE pages hosted by MITRE tend to show up as "RESERVED" for several
weeks or months after assignment.
git_sha1 already puts "--" before its arguments, so
git_sha1_file($dir, 'doc/index.mdwn')
would have incorrectly invoked
git rev-list --max-count=1 HEAD -- -- doc/index.mdwn
If there is no file in the wiki named "--", that's harmless, because
it merely names the latest revision in which either "--" or
"doc/index.mdwn" changed. However, it could return incorrect results
if there is somehow a file named "--".
If we throw an exception (usually from run_or_die), in_git_dir won't
unshift the current directory from the stack. That's usually fine,
but in rcs_preprevert we catch exceptions and do some cleanup before
returning, for which we need the git directory to be the root and
not the temporary working tree.
Some of these might be relatively expensive to dereference or result
in messages being logged, and there's no reason why a search engine
should need to index them. (In particular, we'd probably prefer search
engines to index the rendered page, not its source code.)
We exclude .git/hooks from symlinking into the temporary working tree,
which avoids the commit hook being run for the temporary branch anyway.
This avoids the wiki not being updated if an orthogonal change is
received in process A, while process B prepares a revert that is
subsequently cancelled.
Otherwise, we have a time-of-check/time-of-use vulnerability:
rcs_preprevert previously looked at what changed in the commit we are
reverting, not at what would result from reverting it now. In
particular, if some files were renamed since the commit we are
reverting, a revert of changes that were within the designated
subdirectory and allowed by check_canchange() might now affect
files that are outside the designated subdirectory or disallowed
by check_canchange().
It is not sufficient to disable rename detection, since git older
than 2.8.0rc0 (in particular the version in Debian stable) silently
accepts and ignores the relevant options.
OVE-20161226-0002
This doesn't work prior to git 2.8: `git revert` silently ignores the
option and succeeds. We will have to fix CVE-2016-10026 some other way.
This reverts commit 9cada49ed6.
CGI::FormBuilder->field has behaviour similar to the CGI.pm misfeature
we avoided in f4ec7b0. Force it into scalar context where it is used
in an argument list.
This prevents two (relatively minor) commit metadata forgery
vulnerabilities:
* In the comments plugin, an attacker who was able to post a comment
could give it a user-specified author and author-URL even if the wiki
configuration did not allow for that, by crafting multiple values
to other fields.
* In the editpage plugin, an attacker who was able to edit a page
could potentially forge commit authorship by crafting multiple values
for the rcsinfo field.
The remaining plugins changed in this commit appear to have been
protected by use of explicit scalar prototypes for the called functions,
but have been changed anyway to make them more obviously correct.
In particular, checkpassword() in passwordauth has a known prototype,
so an attacker cannot trick it into treating multiple values of the
name field as being the username, password and field to check for.
OVE-20161226-0001
Previously it was relying on running with an installed ikiwiki
and being able to copy in recentchanges.mdwn and wikiicons/ from the
underlay in /usr. The underlay in ./underlays/basewiki can't be used
(yet) because ikiwiki doesn't allow following symlinks, even from
underlays.
I'd like to make ikiwiki follow symlinks whose destinations can be
verified to be safe (for example making it willing to expose
/usr/share/javascript to the web, but not /etc/passwd), at least from
underlays, but this is security-sensitive so I'm not going to rush
into it.
Simon McVittie
Amitai Schleier
https://anarc.at/openid/
smcv
spalax
intrigeri