Source: disclosure@vulncheck.com
PocketMine-MP versions prior to 4.18.1 contain an improper input validation vulnerability in inventory transaction handling. A remote attacker with a valid player session can request that the server drop more items than are available in the player's hotbar, triggering a server crash and resulting in denial of service.
PocketMine-MP servers are vulnerable to a denial-of-service (DoS) attack. Attackers can exploit an input validation flaw in inventory transaction handling to crash the server by requesting the deletion of more items than a player possesses, leading to service disruption.
Step 1: Player Connection: A valid player establishes a connection to the PocketMine-MP server. Step 2: Crafting/Inventory Interaction: The player interacts with the server's inventory system, such as crafting or moving items. Step 3: Malformed Transaction Request: The attacker crafts a specially crafted inventory transaction request. This request specifies a quantity of items to be dropped from the player's hotbar that exceeds the actual number of items present. Step 4: Server Processing: The server receives the malformed transaction request and attempts to process it. Step 5: Validation Failure: The server's inventory transaction handling logic fails to properly validate the requested item quantity against the available inventory. Step 6: Memory Corruption: The server attempts to remove more items than available, leading to an out-of-bounds read/write operation, potentially corrupting memory. Step 7: Server Crash: The memory corruption triggers a server crash, resulting in a denial-of-service condition.
The vulnerability stems from insufficient input validation within the inventory transaction processing logic. Specifically, the server fails to properly verify the quantity of items a player attempts to drop against the actual number of items present in their hotbar. This leads to an out-of-bounds read or write operation when the server attempts to process the invalid transaction, resulting in a crash. The root cause is a missing or inadequate check on the requested item removal count before attempting to modify the player's inventory data structure. This can be categorized as an integer overflow or underflow condition, leading to memory corruption and server instability.
While no specific APTs are directly linked, this vulnerability is likely to be exploited by script kiddies and individuals seeking to disrupt PocketMine-MP servers. This vulnerability is not listed on the CISA KEV.
Monitor server logs for frequent crashes or unexpected restarts.
Analyze network traffic for suspicious inventory transaction requests, particularly those with large item drop quantities.
Implement intrusion detection systems (IDS) with rules that flag malformed inventory requests.
Monitor server resource usage (CPU, memory) for spikes that may indicate an attack in progress.
Examine server core dumps for memory corruption patterns.
Upgrade to PocketMine-MP version 4.18.1 or later.
Implement input validation to ensure that the requested item drop quantity does not exceed the available inventory.
Regularly back up server data to minimize data loss in the event of a successful attack.
Consider implementing rate limiting on inventory transactions to mitigate the impact of potential exploits.
Review and harden server configuration to limit attack surface.