fix(security): validate upload_file paths to block secret exfiltration#55
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UploadFile passed the caller path straight to DOM.setFileInputFiles with no checks, so an untrusted (page-injected) instruction could upload a local secret — e.g. upload_file(input, "~/.ssh/id_rsa") against an attacker-controlled file input reads and exfiltrates the key. validateUploadPath now resolves the path (following symlinks), requires a regular existing file, and refuses well-known credential material: credential directories (.ssh/.gnupg/.aws/.azure/.kube/.docker/gcloud), private-key/.netrc/ .pgpass base names, and system secret files (/etc/shadow etc.). A focused denylist of things never legitimately uploaded via a browser form. Note: redirect re-validation and per-origin auth-header scoping (the other two security-review items) both require CDP request interception and coexistence with BlockResources — tracked as a separate, design-heavier PR. Claude-Session: https://claude.ai/code/session_01QKTcmXFTKoTQr7mB3HCuHZ
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Problem
UploadFilehanded the caller-supplied path straight toDOM.setFileInputFileswith no validation. Because the MCPupload_filetool is driven by an agent that a malicious page can influence,upload_file(input, "~/.ssh/id_rsa")against an attacker-controlled<input type=file>reads and exfiltrates a local secret.Fix
validateUploadPathnow:.ssh,.gnupg,.aws,.azure,.kube,.docker,gcloudid_rsa/id_dsa/id_ecdsa/id_ed25519,.netrc,.pgpass/etc/shadow,/etc/gshadow,/etc/sudoers,/etc/master.passwdHermetic unit tests cover the denylist logic and the fs checks (regular file, missing, directory, files under
.ssh, files namedid_rsa).Deferred (separate PR)
The other two security-review items — redirect re-validation (a public URL 302-ing to an internal host) and per-origin auth-header scoping (
Network.setExtraHTTPHeaderscurrently leaks theAuthorizationheader to every host) — both require CDP request interception (Fetchdomain) and careful coexistence withBlockResources, plus a per-request-overhead trade-off. They deserve their own focused change rather than being rushed in here.Scout deep-review batch:
upload_filefinding (MEDIUM).https://claude.ai/code/session_01QKTcmXFTKoTQr7mB3HCuHZ