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Re: ADsafe and the Standard Globals

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  • Douglas Crockford
    ... is there another exploit I am not aware of? Those are not standard globals. They are creatures of the DOM. Currently, ADsafe is not granting any access to
    Message 1 of 15 , Apr 10, 2008
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      --- In caplet@yahoogroups.com, "Kris Zyp" <kris@...> wrote:

      > No confirm, alert, or prompt? Preventing annoyance exploits? ;) Or
      is there another exploit I am not aware of?

      Those are not standard globals. They are creatures of the DOM.
      Currently, ADsafe is not granting any access to the DOM. I might relax
      this later. I am relaxing with caution.
    • ♘ stay
      ... Did you mean Math.PI, or is X.PI allowed for any X? -- Mike Stay stay@google.com
      Message 2 of 15 , Apr 10, 2008
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        On Wed, Apr 9, 2008 at 4:48 PM, Douglas Crockford <douglas@...> wrote:
        > Values may be obtain only for these member names:
        >
        > E LN2 LN10 LOG2E LOG10E PI SQRT1_2 SQRT2 MAX_VALUE MIN_VALUE
        > NEGATIVE_INFINITY POSITIVE_INFINITY
        >
        > so
        >
        > Object.PI
        >
        > is allowed.

        Did you mean Math.PI, or is X.PI allowed for any X?
        --
        Mike Stay
        stay@...
      • Douglas Crockford
        ... Yes. It is in anticipation of a decimal package of some sort.
        Message 3 of 15 , Apr 10, 2008
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          --- In caplet@yahoogroups.com, "♘ stay" <stay@...> wrote:

          > Did you mean Math.PI, or is X.PI allowed for any X?

          Yes. It is in anticipation of a decimal package of some sort.
        • David-Sarah Hopwood
          ... I can see the B-movie poster now :-) More seriously, all of the objects that Doug just granted access to, with the exception of Date, provide no authority
          Message 4 of 15 , Apr 10, 2008
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            Douglas Crockford wrote:
            > They are creatures of the DOM.

            I can see the B-movie poster now :-)


            More seriously, all of the objects that Doug just granted access to,
            with the exception of Date, provide no authority -- they only provide
            pure deterministic functions, constant values, and the ability to
            allocate objects of those types (if you don't count that as pure).
            I had come up with exactly the same list for Jacaranda -- except
            that I had accidentially missed out encodeURIComponent.

            Date is an exception just because it grants access to what the Javascript
            implementation thinks the current date/time is, which is technically an
            authority -- but not one that is significant for ADsafe's threat model.

            --
            David-Sarah Hopwood
          • Mike Samuel
            On 10/04/2008, David-Sarah Hopwood ... Date also provides info about the user s locale, but so does Number to some degree.
            Message 5 of 15 , Apr 10, 2008
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              On 10/04/2008, David-Sarah Hopwood
              <david.hopwood@...> wrote:
              >
              >
              >
              >
              >
              >
              > Douglas Crockford wrote:
              > > They are creatures of the DOM.
              >
              > I can see the B-movie poster now :-)
              >
              > More seriously, all of the objects that Doug just granted access to,
              > with the exception of Date, provide no authority -- they only provide
              > pure deterministic functions, constant values, and the ability to
              > allocate objects of those types (if you don't count that as pure).
              > I had come up with exactly the same list for Jacaranda -- except
              > that I had accidentially missed out encodeURIComponent.
              >
              > Date is an exception just because it grants access to what the Javascript
              > implementation thinks the current date/time is, which is technically an
              > authority -- but not one that is significant for ADsafe's threat model.

              Date also provides info about the user's locale, but so does Number to
              some degree.
            • Mark S. Miller
              ... Currently, ADsafe is still approximately a subset of Caja. Were these added, it would cause significant breakage of the subset relationship. -- Cheers,
              Message 6 of 15 , Apr 10, 2008
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                On Wed, Apr 9, 2008 at 10:17 PM, Kris Zyp <kris@...> wrote:
                > No confirm, alert, or prompt? Preventing annoyance exploits? ;) Or is there
                > another exploit I am not aware of?

                Currently, ADsafe is still approximately a subset of Caja. Were these
                added, it would cause significant breakage of the subset relationship.

                --
                Cheers,
                --MarkM
              • David-Sarah Hopwood
                ... and timezone ... And Array.prototype.toLocaleString, and String.prototype.localeCompare. Thanks for pointing this out -- it s better to have any ambient
                Message 7 of 15 , Apr 11, 2008
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                  Mike Samuel wrote:
                  > On 10/04/2008, David-Sarah Hopwood
                  > <david.hopwood@...> wrote:
                  >> Douglas Crockford wrote:
                  >> > They are creatures of the DOM.
                  >>
                  >> I can see the B-movie poster now :-)
                  >>
                  >> More seriously, all of the objects that Doug just granted access to,
                  >> with the exception of Date, provide no authority -- they only provide
                  >> pure deterministic functions, constant values, and the ability to
                  >> allocate objects of those types (if you don't count that as pure).
                  >> I had come up with exactly the same list for Jacaranda -- except
                  >> that I had accidentially missed out encodeURIComponent.
                  >>
                  >> Date is an exception just because it grants access to what the Javascript
                  >> implementation thinks the current date/time

                  and timezone

                  >> is, which is technically an authority -- but not one that is significant
                  >> for ADsafe's threat model.
                  >
                  > Date also provides info about the user's locale, but so does Number to
                  > some degree.

                  And Array.prototype.toLocaleString, and String.prototype.localeCompare.
                  Thanks for pointing this out -- it's better to have any ambient authority
                  that we decide to allow thoroughly documented.

                  --
                  David-Sarah Hopwood
                • Mark Miller
                  On Fri, Apr 11, 2008 at 2:13 PM, David-Sarah Hopwood ... In addition to the violations noted later in this thread, there s also Math.random(). -- Text by me
                  Message 8 of 15 , Apr 11, 2008
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                    On Fri, Apr 11, 2008 at 2:13 PM, David-Sarah Hopwood
                    <david.hopwood@...> wrote:
                    > >> More seriously, all of the objects that Doug just granted access to,
                    > >> with the exception of Date, provide no authority -- they only provide
                    > >> pure deterministic functions, constant values, and the ability to
                    > >> allocate objects of those types (if you don't count that as pure).

                    In addition to the violations noted later in this thread, there's also
                    Math.random().


                    --
                    Text by me above is hereby placed in the public domain

                    Cheers,
                    --MarkM
                  • Douglas Crockford
                    ... It is in the standard and it does not represent a leak. escape is not recommended for encoding URLs, but can be used for encoding values in cookies. Unless
                    Message 9 of 15 , Apr 15, 2008
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                      --- In caplet@yahoogroups.com, "Mike Samuel" <mikesamuel@...> wrote:
                      > > I am relaxing ADsafe to allow access to these standard globals:
                      > >
                      > > Array Boolean Date decodeURI decodeURIComponent encodeURI
                      > > encodeURIComponent Error escape EvalError isFinite isNaN
                      > > Math Number Object parseInt parseFloat RangeError
                      > > ReferenceError RegExp String SyntaxError TypeError unescape
                      > > URIError
                      >
                      > Is it really worth including {,un}escape in light of
                      > http://msdn2.microsoft.com/en-us/library/9yzah1fh(VS.85).aspx ?
                      > Is it a goal to support older versions of JS that don't have
                      > {de,en}codeURIComponent?

                      It is in the standard and it does not represent a leak. escape is not
                      recommended for encoding URLs, but can be used for encoding values in
                      cookies. Unless there is a stronger argument, I think it should be
                      allowed.

                      > Is RegExp.$1 is not allowed? If so, it may leak information from the
                      > last match performed by privileged code.

                      RegExp.$1 is not allowed because $1 is not the name of one of the
                      Math/Number constants.

                      RegExp['$1'] is not allowed because '$1' does not look like a
                      stringified number.

                      ADsafe.get(RegExp, '$1') is not allowed because RegExp is a function.
                    • Mike Samuel
                      ... I have no stronger argument than, in code I review, it is much more frequently misused than used properly. If the goal is to allow all innocuous ES
                      Message 10 of 15 , Apr 15, 2008
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                        On 15/04/2008, Douglas Crockford <douglas@...> wrote:
                        >
                        >
                        >
                        >
                        >
                        >
                        > --- In caplet@yahoogroups.com, "Mike Samuel" <mikesamuel@...> wrote:
                        > > > I am relaxing ADsafe to allow access to these standard globals:
                        > > >
                        > > > Array Boolean Date decodeURI decodeURIComponent encodeURI
                        > > > encodeURIComponent Error escape EvalError isFinite isNaN
                        > > > Math Number Object parseInt parseFloat RangeError
                        > > > ReferenceError RegExp String SyntaxError TypeError unescape
                        > > > URIError
                        > >
                        > > Is it really worth including {,un}escape in light of
                        > > http://msdn2.microsoft.com/en-us/library/9yzah1fh(VS.85).aspx ?
                        > > Is it a goal to support older versions of JS that don't have
                        > > {de,en}codeURIComponent?
                        >
                        > It is in the standard and it does not represent a leak. escape is not
                        > recommended for encoding URLs, but can be used for encoding values in
                        > cookies. Unless there is a stronger argument, I think it should be
                        > allowed.

                        I have no stronger argument than, in code I review, it is much more
                        frequently misused than used properly.

                        If the goal is to allow all innocuous ES built-ins, then it should be allowed.



                        > > Is RegExp.$1 is not allowed? If so, it may leak information from the
                        > > last match performed by privileged code.
                        >
                        > RegExp.$1 is not allowed because $1 is not the name of one of the
                        > Math/Number constants.
                        >
                        > RegExp['$1'] is not allowed because '$1' does not look like a
                        > stringified number.
                        >
                        > ADsafe.get(RegExp, '$1') is not allowed because RegExp is a function.

                        Cool.
                      • Mark S. Miller
                        On Tue, Apr 15, 2008 at 4:42 PM, Douglas Crockford ... I just looked. They are not in the normative part of the ES3 spec. They appear only in Annex B. (B.2.1 &
                        Message 11 of 15 , Apr 15, 2008
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                          On Tue, Apr 15, 2008 at 4:42 PM, Douglas Crockford
                          <douglas@...> wrote:
                          > > Is it really worth including {,un}escape in light of
                          > > http://msdn2.microsoft.com/en-us/library/9yzah1fh(VS.85).aspx ?
                          > > Is it a goal to support older versions of JS that don't have
                          > > {de,en}codeURIComponent?
                          >
                          > It is in the standard [...]

                          I just looked. They are not in the normative part of the ES3 spec.
                          They appear only in Annex B. (B.2.1 & B.2.2)

                          They have never appeared in the Caja whitelist, and probably never
                          will. So they are not in any of the normative supersets of ADsafe.

                          --
                          Cheers,
                          --MarkM
                        • Douglas Crockford
                          ... And they are no longer in ADsafe. JSLint will flag them in all cases.
                          Message 12 of 15 , Apr 15, 2008
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                            --- In caplet@yahoogroups.com, "Mark S. Miller" <erights@...> wrote:
                            > I just looked. They are not in the normative part of the ES3 spec.
                            > They appear only in Annex B. (B.2.1 & B.2.2)
                            >
                            > They have never appeared in the Caja whitelist, and probably never
                            > will. So they are not in any of the normative supersets of ADsafe.

                            And they are no longer in ADsafe. JSLint will flag them in all cases.
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