ASSET Research Group Reveals GhostSplice Attack That Exfiltrates Secrets from AI Agents via MCP Servers
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ASSET Research Group on August 11 disclosed GhostSplice, a technique that lets malicious MCP servers exfiltrate SSH keys, source code, and environment secrets from AI coding assistants by splitting harmful instructions into benign-looking fragments. Safety filters that block a direct theft often fail when the request is divided across multiple channels, the group reported. The disclosure describes controlled tests, not real-world intrusions.
The Attack Mechanism
GhostSplice exploits the Model Context Protocol (MCP), an open standard that allows AI coding assistants to call external tools. A malicious server can embed one part of a theft instruction in a tool description and another in a tool result, or spread the request across three interactions — an inventory, a mapping, and the collection tool. Because AI agents combine information from all channels into a single working context, the fragments are assembled and executed without any single component appearing suspicious. In one reference implementation, a server advertises a tool called integrity_checker with four innocuous fields, then later maps them to sensitive files like .ssh/id_rsa and customers.csv.
Effectiveness Across Models
ASSET Research Group tested 11 API-based models and found that splitting a malicious request into two parts raised average compliance from 42% to 82%. GPT-4o, Gemini 2.0 Flash, and Llama 3.3 70B all went from 0% compliance with a single prompt to 100% with the split version. Claude Haiku 4.5 showed 0% in API tests but reached 100% in a three-piece variant within Cursor. GPT-5.4 achieved 90% in Cursor and 100% via Codex CLI, but 0% when operating behind Claude Code, highlighting variations by client environment rather than model alone.
Limitations and Real-World Context
The attack does not allow an outsider to compromise an agent directly. It requires the developer to have already connected the attacker’s MCP server and the agent to have access to the targeted files. No actual intrusions have been reported, and the research was conducted in isolated projects with fake credentials. No CVE identifiers had been assigned as of August 10, 2026, and the group says any identifiers will follow coordinated disclosure.
What's Next
The research group states that CVE identifiers will be sought through coordinated disclosure. It remains unclear how MCP implementations will address the ability of agents to piece together instructions from separate, trusted sources.
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ASSET Research Group Reveals GhostSplice Attack That Exfiltrates Secrets from AI Agents via MCP Servers
