Afs3-fileserver Exploit 'link'

AFS3-fileserver service, which typically runs on port 7000/TCP , is often associated with the Andrew File System (AFS)

. While there is no single "afs3-fileserver" exploit, multiple vulnerabilities have been documented in the OpenAFS fileserver and its associated Rx RPC protocol Common Vulnerabilities Buffer Overflows (CVE-2013-1794): afs3-fileserver exploit

Are you currently managing an OpenAFS cell, or are you researching this for a security audit? AI responses may include mistakes. Learn more The server allocates a buffer on the stack or heap

The fileserver process (the core daemon that manages volume data) listened on UDP port 7000. For decades, security researchers glanced at it and moved on. It was old. It was obscure. It was "probably fine." The afs3-fileserver exploit targets a vulnerability in the

  1. The server allocates a buffer on the stack or heap.
  2. The memcpy operation copies the user-supplied data into the fixed-size structure.
  3. Because bounds checking is absent or insufficient, the copy overwrites adjacent memory (stack canaries or heap metadata).

The afs3-fileserver exploit targets a vulnerability in the AFS implementation, specifically in the way it handles file server requests. The vulnerability allows an attacker to execute arbitrary code on the file server, potentially leading to a complete compromise of the system.

Step 3 – Exploitation
If successful, the server replies with the volume ID of /afs/.root.cell — without ever checking if the requester has valid tokens. From there:

  • Issue: Certain RPC opcodes skip token validation entirely if the caller claims to be the “system:administrator” group via a crafted ViceId.
  • Root cause: A memcmp() that compares tokens but doesn’t verify expiration, issuer, or cell — only a static credential hash if the connection flags are “special.”
  • Exploit primitive: Send a packet with flags=0xDEADBEEF and token->kvno = 0 → fileserver enters “legacy compat mode” and grants full volume access.

The exploit consists of three stages:

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