Sparkle Project vulnerabilities and threats

Sparkle is a software update framework for macOS. In versions up to and including 2.9.1, `Autoupdate/AppInstaller.m`'s `shouldAcceptNewConnection:` only enforces `SUCodeSigningVerifier validateConnection:` before stage 1 completes. After `_performedStage1Installation = YES`, new connections to the registered Mach service `<bundleId>-spki` are accepted from any local process without team-ID or code-signing checks. As of time of publication, no known patched versions are available.

Sparkle is a software update framework for macOS. Prior to version 2.9.2, `Autoupdate/SUBinaryDeltaApply.m` enforces `relativePath.pathComponents containsObject:@".."` and rejects writes whose immediate parent directory IS itself a symbolic link, but does not detect symlinks deeper in the relative path. `Autoupdate/SPUSparkleDeltaArchive.m`'s `extractItem:` will create symlinks in the destination tree from archive content (no `..` check on the symlink target), and a subsequent `Extract` item targeting `<symlink>/foo/bar` then escapes the destination tree via `fopen(path, "wb")` because the kernel resolves the intermediate symlink during the open call. This is a defense-in-depth issue: exploitation requires a maliciously-crafted `.delta` that passes EdDSA signature verification, i.e. EdDSA private-key compromise. With the AppInstaller running as root for system-domain installs, it gives the holder of a stolen signing key arbitrary file write at root level via the delta-apply path, which is a strictly broader primitive than the "drop-in replacement bundle" install they would otherwise have. Version 2.9.2 contains a patch for the issue.

The Sparkle framework includes a helper tool Autoupdate. Due to lack of authentication of connecting clients a local unprivileged attacker can request installation of crafted malicious PKG file by racing to connect to the daemon when other app spawns it as root. This results in local privilege escalation to root privileges. It is worth noting that it is possible to spawn Autopudate manually via Installer XPC service. However this requires the victim to enter credentials upon system authorization dialog creation that can be modified by the attacker. This issue was fixed in version 2.7.2

The Sparkle framework includes an XPC service Downloader.xpc, by default this service is private to the application its bundled with. A local unprivileged attacker can register this XPC service globally which will inherit TCC permissions of the application. Lack of validation of connecting client allows the attacker to copy TCC-protected files to an arbitrary location. Access to other resources beyond granted-permissions requires user interaction with a system prompt asking for permission. This issue was fixed in version 2.7.2