androidandroid-layoutsecurityandroid-jetpack-composeandroid-jetpack

Jetpack Compose Tapjacking: Filter touches on obscured UI


While there is abundant documentation on Tapjacking in tradition XML views in Android to prevent malicious apps from interacting with sensitive information, there appears to be none around the issue for Jetpack Compose.

Is there an equivalent to filterTouchesWhenObscured for @Composables, was this issue solved at a more fundemental level, or does custom logic need to be implemented with gesture/touch modifiers?


Solution

  • There's no way to specify filterTouchesWhenObscured for a specific composable, and according to this maintainer comment it's not currently planned:

    We won't likely implement it beyond the ComposeView level in the near future.

    But you can do it for ComposableView which is used to draw Compose tree. For example, if you to apply it to the whole screen while some particular view is on the screen, you can do it like this:

    val composeView = LocalView.current
    
    DisposableEffect(Unit) {
        composeView.filterTouchesWhenObscured = true
        onDispose {
            composeView.filterTouchesWhenObscured = false
        }
    }
    

    Alternatively, if you want to apply it for a particular composable, like to only part of the screen, you can use such wrapper:

    @Composable
    fun ObscuredView(
        content: @Composable () -> Unit,
    ) {
        AndroidView(
            factory = {
                ComposeView(it).apply {
                    filterTouchesWhenObscured = true
                }
            },
            update = {
                it.setContent(content)
            }
        )
    }
    

    Usage:

    ObscuredView {
        Text("this text is Obscured")
    }