[tbb-bugs] #18537 [Tor Browser]: Resist keyboard and mouse biometrics and tracking

Tor Bug Tracker & Wiki blackhole at torproject.org
Sat Mar 12 19:02:06 UTC 2016


#18537: Resist keyboard and mouse biometrics and tracking
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     Reporter:  cypherpunks  |      Owner:  tbb-team
         Type:  enhancement  |     Status:  new
     Priority:  Medium       |  Milestone:
    Component:  Tor Browser  |    Version:
     Severity:  Normal       |   Keywords:
Actual Points:               |  Parent ID:
       Points:               |   Reviewer:
      Sponsor:               |
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 Hi, I think TBB should resist keyboard and mouse biometrics better. This
 will prowide protection against mouse pointer tracking for implicit
 detection us user's interests.

 1 when page is loaded
         a) TBB records all mouse and keyboard events, except mouse move,
 if JS is enabled. The page doesn't get keyboard and mouse events at all.
         b) TBB records the time the page is loaded.

 2 When submit event is triggered
         a) TBB stops capturing events
         b) TBB analyse the events.
         c) TBB simulates the events

 3 Events analysis
         Let a user interacting with visible gui elements: <textarea>s,
 <option>s, text fields, buttons and another <input>s.
         Then when the form is submited, a user has all the fields filled
 with the needed data. He needs to provide a website with the filled data
 ignoring all the information about the way they have been filled.

         a) create a list of elements
         b) when an element gets focus and if it is not in the list, push
 it into the end of the list
         c) when all events are processed the list of elements is ordered
 by the first time they were activated by the user
         d) then TBB can create simulated events for these elements based
 on their state in the end of interaction and the order of their
 activation.

 4  Event simulation
         a) TBB creates a variable for the time counter and the virtual
 mouse pointer (vmp) coordinates
         b) TBB loads saved time into it.
         a) TBB chooses virtual vmp position according to selected model
         c) TBB delays according to selected model because a user cannot
 start interacting with page immediately
         d) TBB sorts the GUI elements according the order a user is able
 to activate them by hitting <TAB> key.
         c) TBB chooses model of user a sampling all the params of the
 model using probability distribution functions.
         e) TBB simulates input events

 5 Input events simulation cycle
 a) TBB simulates GUI element getting focus according to selected model
 b) TBB simulates user interaction with GUI element according to selected
 model
 a) TBB simulates GUI element loosing focus according to selected model


 6 Mouse events simulation (getting focus and interaction)
         a) TBB creates mousemove events according to selected model and
 changes vmp position
         b) TBB creates mousedown event according to selected model
         c) TBB creates mousepress event according to selected model
         d) TBB creates mouseup event according to selected model
         d) TBB creates either click or contextmenu event according to
 selected model

 7 Keyboard events simulation (changing focuf with TAB or user input)
         a) TBB creates keydown event according to selected model
         a) TBB creates keypress event according to selected model
         a) TBB creates keyup event according to selected model

 8 Mouse movement model
         The model params are
         let t_ev be a time to the next event
         let t_l be delay of vmp leaving element

         let r={x,y} be vmp coordinates
         let r_prev={r_prev_x,r_prev_y}

         let v={v_x,v_y} be vmp speed
         let v_st be magnitude of speed of pointer in the middle of its way
         let phi_l be variation of angle from the line connecting the 2
 endpoints

         let f be a factor of decelleration

         let mag(v) be a magnitude of vector v
         let rot(phi) be a rotation matrix
         let exp(x) be an exponent
         . is dot product

         a sample all the params from models using probability distribution
 functions.
         b determine the endpoint r_t within the target element as as a
 sample from uniform distribution
         c t+=t_l wait the t_l
         in loop
                 d sample t_ev, v_st and phi_l from the model
                 e calculate the vector from vmp to endpoint dr=r_t-r
                 f calculate director d=dr/mag(dr)
                 j mag(v)=v_st * exp(-mag(dr)/f)
                 h calculate ds = t_ev * mag(v)
                 i if overshoot (ds > mag(dr))
                         ii ds = mag(dr)
                         iii mag(v) = ds / t_ev

                 k rotate director d.rot(phi_l)
                 l v = d * mag(v)
                 m r+= v*t_ev

                 n shift clock t+=t_ev
                 o emit mousemove event
                 p if the cursor in place (ds >= mag(r)) break the loop
 7 Keyboard and mouse button model
         let t_d be delay before down event
         let t_c be delay between down and click
         let t_u be delay between down and up
         let t_p be interval between press events
         let t_p_th be threshold time for press events

         a sample all the params from models using probability distribution
 functions.
         b td+=t_d
         c tu=t+t_u
         d tc=t+t_c
         e tp_th=t+t_p_th
         f emit down event
         g if the device is mouse emit either click or context menu event
 with t=tc
         h if tu>tp_th
                 for t in range(tp_th,tu,t_p)
                         emit press event
         i emit up event with t=tu

 8 The distributions for delays can be derived using Amazon Mechanical Turk
 with hand postprocessing to remove fake instances. Another way is to
 create an arcade game where players should enter text and click text
 fields as fast as they can in order to win.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/18537>
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