Bootstrap token persists on disk with weak file permissions #59

New Issue

Skipper · 2026-04-05T16:23:05Z

Skipper commented

2026-04-05 16:23:05 +00:00

Info

Severity: HIGH
Attack vector: local malicious process

Impact

Allows a local attacker to steal the bootstrap token, register a malicious user agent, and potentially take permanent control of the vault bootstrap flow.

Description

The bootstrap token is written to ~/.arbiter/bootstrap_token using default file permissions and is never deleted after successful consumption. That leaves the token readable to other local processes running under the same UID, and possibly to other users depending on directory permissions. It also leaves a long-lived sensitive artifact on disk even after bootstrap is complete.

Example flow

Read ~/.arbiter/bootstrap_token from disk before or after legitimate bootstrap.
Present the token to the server before the legitimate user agent does.
Register an attacker-controlled user-agent key.
Bootstrap the vault using attacker-controlled credentials and retain long-term authority.

Mitigation

Create the file with mode 0o600 and delete it immediately after successful token consumption.

# Info **Severity**: **HIGH** Attack vector: local malicious process ## Impact Allows a local attacker to steal the bootstrap token, register a malicious user agent, and potentially take permanent control of the vault bootstrap flow. ## Description The bootstrap token is written to `~/.arbiter/bootstrap_token` using default file permissions and is never deleted after successful consumption. That leaves the token readable to other local processes running under the same UID, and possibly to other users depending on directory permissions. It also leaves a long-lived sensitive artifact on disk even after bootstrap is complete. ## Example flow 1. Read `~/.arbiter/bootstrap_token` from disk before or after legitimate bootstrap. 2. Present the token to the server before the legitimate user agent does. 3. Register an attacker-controlled user-agent key. 4. Bootstrap the vault using attacker-controlled credentials and retain long-term authority. ## Mitigation Create the file with mode `0o600` and delete it immediately after successful token consumption.

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Reference: MarketTakers/arbiter#59