---
id: "nr-the-coding-agent-installed-on-a-developer-s-machine-is-now-an-attack-t-01ac6e"
slug: "the-coding-agent-installed-on-a-developer-s-machine-is-now-an-attack-t-01ac6e"
type: "raw_signal"
title: "The coding agent installed on a developer's machine is now an attack target that must be inventoried and pinned"
description: "Attackers are tampering with the agent clients themselves."
observed_at: "2026-10-31"
record_date: "2026-10-31"
date_kind: "observed_at"
novelty: "notable"
source_platform: "newruntime.com"
topics: ["claude","claude-code","codex"]
entities: ["Symantec","Symantec Threat Hunter Team","OpenAI","Codex","Anthropic","Claude Code","Cursor","Cursor Extension Marketplace","Visual Studio Code","Microsoft"]
related_patterns: ["agent-security-moves-to-runtime-boundaries","harness-architecture-outlives-model-choice","agent-ready-software-exposes-capabilities"]
source_url: "https://www.security.com/threat-intelligence/openai-claude-unauthorized-relays"
source_urls: ["https://www.security.com/threat-intelligence/openai-claude-unauthorized-relays","https://cursor.com/blog/claude-code-extension-security-notice","https://techcommunity.microsoft.com/blog/MicrosoftThreatProtectionBlog/now-generally-available-discover-local-ai-agents-with-microsoft-defender/4568216","https://github.blog/changelog/2026-10-13-enterprise-managed-settings-enforcement-updates","https://adversa.ai/agent-security-platform"]
why_it_matters: "Attackers are tampering with the agent clients themselves. A grey-market relay installs genuine Codex and Claude Code CLIs, then disables their sandboxes and reroutes their traffic, and a malicious Claude Code extension build reached up to 5,000 Cursor users. Defenders are responding at the client: Microsoft Defender now finds local agents and their MCP servers, and GitHub can require a minimum Copilot client version and fresh policy at startup."
verification_level: "source-linked"
signal_type: "synthesis"
synthesis_of: [{"slug":"symantec-grey-market-relay-installs-real-codex-and-d143b3","title":"Symantec: grey-market relay installs real Codex and Claude Code CLIs, then disables their sandboxes and reroutes traffic","url":"https://newruntime.com/posts/symantec-grey-market-relay-installs-real-codex-and-d143b3/"},{"slug":"malicious-claude-code-extension-v2-1-313-hit-d4c504","title":"Malicious Claude Code extension v2.1.313 hit Cursor's marketplace, exposing up to 5,000 developers.","url":"https://newruntime.com/posts/malicious-claude-code-extension-v2-1-313-hit-d4c504/"},{"slug":"microsoft-defender-discovery-of-local-ai-agents-and-b4e565","title":"Microsoft Defender discovery of local AI agents and their MCP servers is now generally available","url":"https://newruntime.com/posts/microsoft-defender-discovery-of-local-ai-agents-and-b4e565/"},{"slug":"github-lets-enterprises-force-fresh-copilot-policy-at-88951a","title":"GitHub lets enterprises force fresh Copilot policy at startup and enforce a minimum client version for the sandbox key","url":"https://newruntime.com/posts/github-lets-enterprises-force-fresh-copilot-policy-at-88951a/"},{"slug":"adversa-ai-launches-coding-agent-security-platform-for-282ec1","title":"Adversa AI launches Coding Agent Security Platform for Claude Code, Codex and agentic IDEs","url":"https://newruntime.com/posts/adversa-ai-launches-coding-agent-security-platform-for-282ec1/"}]
schema_version: "newruntime-agent-readable-v0.2"
stable_id: "signal:the-coding-agent-installed-on-a-developer-s-machine-is-now-an-attack-t-01ac6e"
retrieval_nugget: "Attackers are tampering with the agent clients themselves. A grey-market relay installs genuine Codex and Claude Code CLIs, then disables their sandboxes and reroutes their traffic, and a malicious Claude Code extension build reached up to 5,000 Cursor users."
status: "published"
visuals: []
editor: {"role":"editor","name":"Andrey Reshetnikov","profile":"https://newruntime.com/owner-profile.md","profile_json":"https://newruntime.com/owner-profile.json","same_as":["https://www.linkedin.com/in/reshetnikov1/","https://t.me/lapetuse"]}
routes: {"html":"https://newruntime.com/signals/the-coding-agent-installed-on-a-developer-s-machine-is-now-an-attack-t-01ac6e/","markdown":"https://newruntime.com/signals/the-coding-agent-installed-on-a-developer-s-machine-is-now-an-attack-t-01ac6e.md","json":"https://newruntime.com/signals/the-coding-agent-installed-on-a-developer-s-machine-is-now-an-attack-t-01ac6e.json"}
---

# The coding agent installed on a developer's machine is now an attack target that must be inventoried and pinned

## Retrieval answer

Attackers are tampering with the agent clients themselves. A grey-market relay installs genuine Codex and Claude Code CLIs, then disables their sandboxes and reroutes their traffic, and a malicious Claude Code extension build reached up to 5,000 Cursor users.

Attackers are tampering with the agent clients themselves. A grey-market relay installs genuine Codex and Claude Code CLIs, then disables their sandboxes and reroutes their traffic, and a malicious Claude Code extension build reached up to 5,000 Cursor users. Defenders are responding at the client: Microsoft Defender now finds local agents and their MCP servers, and GitHub can require a minimum Copilot client version and fresh policy at startup.

From the Field Notes:

- [Symantec: grey-market relay installs real Codex and Claude Code CLIs, then disables their sandboxes and reroutes traffic](https://newruntime.com/posts/symantec-grey-market-relay-installs-real-codex-and-d143b3/) (2026-10-31)
- [Malicious Claude Code extension v2.1.313 hit Cursor's marketplace, exposing up to 5,000 developers.](https://newruntime.com/posts/malicious-claude-code-extension-v2-1-313-hit-d4c504/) (2026-10-31)
- [Microsoft Defender discovery of local AI agents and their MCP servers is now generally available](https://newruntime.com/posts/microsoft-defender-discovery-of-local-ai-agents-and-b4e565/) (2026-10-31)
- [GitHub lets enterprises force fresh Copilot policy at startup and enforce a minimum client version for the sandbox key](https://newruntime.com/posts/github-lets-enterprises-force-fresh-copilot-policy-at-88951a/) (2026-10-31)
- [Adversa AI launches Coding Agent Security Platform for Claude Code, Codex and agentic IDEs](https://newruntime.com/posts/adversa-ai-launches-coding-agent-security-platform-for-282ec1/) (2026-10-31)

Editor: [Andrey Reshetnikov](https://newruntime.com/owner-profile.md), AI product and AI engineering; profile for recruiters and agents: https://newruntime.com/owner-profile.json

## Continue in the graph

Next records for an agent, linked to their Markdown twins. Replace `.md` with `.json` for structured fields, including `next_reads`.

- topic hub: [Claude](https://newruntime.com/topics/claude.md): Explore the claude topic hub.
- topic hub: [Claude Code](https://newruntime.com/topics/claude-code.md): Explore the claude-code topic hub.
- topic hub: [Codex](https://newruntime.com/topics/codex.md): Explore the codex topic hub.
- collection: [Raw Signals](https://newruntime.com/signals.json): Open every source-linked raw signal.
- collection: [Source Ledger](https://newruntime.com/source-ledger.json): Inspect the public source evidence graph.
- whole graph: [discovery graph](https://newruntime.com/discovery-graph.json) (typed nodes and edges) and [site index](https://newruntime.com/site-index.md)