RUNTIMEWIRE INVESTIGATION — Scoop Original reporting by RuntimeWire, based on reverse engineering, data analysis, documents. Why it matters Kimi Desktop's updater trusts control of a mutable download location as authority to install code. A release-system compromise could therefore reach local agents without Moonshot's signing key. Reporting record Finding Kimi Desktop 3.1.5 and 3.1.10 automatically install and update a separate Group Chat executable and three agent skills from mutable Moonshot CDN locations, while the Windows updater skips checksum verification and does not enforce the executable’s Authenticode signer before installation. How we verified Methods: reverse engineering, data analysis, documents. RuntimeWire traced Kimi Desktop’s packaged updater from triggerKimiimColdStartCheck() through its download, fingerprinting, verification and installation logic. The updater sets its release version to latest and downloads kimiim-cli from a mutable Moonshot CDN tree under: https://kimi-img.moonshot.cn/pub/claw/tmp/lihuaru/skills/kimiim It determines whether to update using an HTTP HEAD request and compares ETag, Last-Modified or content length with a locally stored fingerprint. The code does not pin a release version or require an authenticated release manifest. Checksum verification is guarded by an operating-system condition equivalent to: if (os !== "windows") { verifyChecksum(...) } The live Windows ZIP contains kimiim-cli.exe without a checksum file. The installer does not call Get-AuthenticodeSignature, validate a certificate identity or otherwise enforce an expected signer before moving the executable into ~/.local/bin. The installed executable is currently signed with a valid Moonshot Authenticode certificate. That signature is an important qualification: the artifact RuntimeWire examined was signed, while the updater code does not require future replacements to carry that signature. The installer removes the previous target, renames the downloaded executable into ~/.local/bin/kimiim-cli.exe and permanently adds ~/.local/bin to the Windows user PATH. Three agent skills are updated from mutable paths through the same ETag/Last-Modified mechanism: kimiim/SKILL.md worker-safety/SKILL.md time-awareness/SKILL.md The macOS archive includes a checksum beside its binary, although the checksum and binary arrive together through the same mutable download. The archive also retains developer packaging metadata, including AppleDouble files, quarantine and provenance attributes, and ownership metadata identifying houzhendong/staff. The native executable identifies the Go module kimi.darkmatter/tools/kimiim-cli, commit 231e0b9d475dcc0d99db0da712477014d97f575c, and build time 2026-04-25T04:57:57Z. RuntimeWire found no evidence that Moonshot’s CDN, publishing credentials or distributed artifacts have been compromised. RuntimeWire extracted and examined the packaged JavaScript from Kimi Desktop 3.1.5 for Windows. We located the Group Chat cold-start function and followed its control flow through URL construction, update detection, checksum handling, installation and PATH modification. We inspected the live Windows archive delivered by Moonshot, recorded its HTTP metadata, listed its contents and calculated SHA-256 hashes for the archive and executable. We used Windows Authenticode inspection to verify the executable’s current signature status and inspected Go build metadata and embedded strings without altering the binary. We separately inspected the macOS archive structure, included checksum and retained packaging metadata. We compared the relevant packaged updater code with Kimi Desktop 3.1.10 and confirmed that the mutable Group Chat update mechanism and Windows checksum exception remained present in that release. For limited behavioral testing of the Group Chat CLI, we used a Linux build with a dummy token and a reporter-controlled loopback capture server. We did not connect a real Group Chat account, replace any Moonshot artifact or attempt to execute code on another user’s installation. RuntimeWire disclosed the finding to Moonshot Security on Aug. 14, 2026. Moonshot was asked to acknowledge the disclosure by 6 p.m. CDT on Aug. 15 and was offered a short publication delay if remediation was underway. Moonshot did not reply before publication. Tested versions: Kimi Desktop 3.1.5, release identifier 3.1.5+c88420152, Windows x64 Kimi Desktop 3.1.10, release identifier 3.1.10+e0c4c9980, Windows x64. Reproduction RuntimeWire independently reproduced the core finding. Requirements: Kimi Desktop 3.1.5 or 3.1.10 for Windows x64 A disposable Windows test environment An ASAR extraction tool PowerShell No Group Chat token is required for static verification Steps: Obtain the official Kimi Desktop Windows release and extract its packaged app.asar. Search the extracted application for triggerKimiimColdStartCheck. Follow the call into the kimiim-cli installer and updater. Confirm that the configured version string is la...