NoSlow Grim Old Bypass

[skr4tchh]

Describe the bypass and how to replicate it

mc.player.connection.sendPacket(new CPlayerTryUseItemPacket(Hand.MAIN_HAND));

This bypass has been working for about a year now, and if you stand still for a while and then start running, it will work. It also works perfectly if you have food in your main hand and a shield or bow in your other hand.

Grim version

Grim 2.3.71

Server version

1.16.5

Plugins

GrimAC

[ManInMyVan]

try on the latest commit

[skr4tchh]

try on the latest commit

No, it still works the same way in the last commit.

[ManInMyVan]

mc.player.connection.sendPacket(new CPlayerTryUseItemPacket(Hand.MAIN_HAND));

this is literally just using the item

[skr4tchh]

mc.player.connection.sendPacket(new CPlayerTryUseItemPacket(Hand.MAIN_HAND));

this is literally just using the item

However, if you spam this package, the bypass will work.

[skr4tchh]

You can check it yourself.

[skr4tchh]

I've written situations where it works great.

[skr4tchh]

mc.player.connection.sendPacket(new CPlayerTryUseItemPacket(Hand.MAIN_HAND));

this is literally just using the item

                if(mc.player.getActiveHand() == Hand.OFF_HAND) {
                    mc.player.connection.sendPacket(new CPlayerTryUseItemPacket(Hand.MAIN_HAND));
                }

[skr4tchh]

I know you already have a fix for this, but it doesn't really help.

[ManInMyVan]

ah I see what's happening here, this is abusing the resync we apply for food items

[skr4tchh]

ah I see what's happening here, this is abusing the resync we apply for food items

Can you fix it?

[Eur0papa]

I fixed this NoSlow in my personal fork of GrimAC, no false positives, I can create a PR

[skr4tchh]

So will you fix the bypass or not?

[skr4tchh]

I fixed this NoSlow in my personal fork of GrimAC, no false positives, I can create a PR

Can you send a fix?

[skr4tchh]

@skr4tchh No false positive for 1.9+ found

@checkdata(name = "NoSlow", description = "Was not slowed while using an item") public class NoSlow extends Check implements PostPredictionCheck { double offsetToFlag; double bestOffset = 1; // The player sends that they switched items the next tick if they switch from an item that can be used // to another item that can be used. What the fuck mojang. Affects 1.8 (and most likely 1.7) clients. public boolean didSlotChangeLastTick = false; public boolean flaggedLastTick = false; private long buffer;

public NoSlow(GrimPlayer player) {
    super(player);
}

@Override
public void onPredictionComplete(final PredictionComplete predictionComplete) {
    if (!predictionComplete.isChecked()) return;

    // If the player was using an item for certain, and their predicted velocity had a flipped item
    if (player.packetStateData.isSlowedByUsingItem() && buffer++ > 3) {
        // 1.8 users are not slowed the first tick they use an item, strangely
        if (player.getClientVersion().isOlderThanOrEquals(ClientVersion.V_1_8) && didSlotChangeLastTick) {
            didSlotChangeLastTick = false;
            flaggedLastTick = false;
        }

        if (bestOffset > offsetToFlag) {
            if (flaggedLastTick) {
                BukkitNMS.resetBukkitItemUsage(player.bukkitPlayer);
                if (buffer > 6) {
                    flagAndAlert("buffer=" + buffer);
                }
            }
            flaggedLastTick = true;
        } else {
            reward();
            flaggedLastTick = true;
            buffer = 0;
        }
    }
    bestOffset = 1;
}

public void handlePredictionAnalysis(double offset) {
    bestOffset = Math.min(bestOffset, offset);
}

@Override
public void onReload(ConfigManager config) {
    offsetToFlag = config.getDoubleElse(getConfigName() + ".threshold", 0.001);
}

}

It doesn't fix anything.