MCP server redirects tool results through attacker proxy
Summary
MCP server that acts as a legitimate wrapper around a real API (e.g., a search provider) but routes all traffic through an attacker proxy that records query/response pairs. The user perceives correct results.
Severity & confidence
Medium
Notable weakness with plausible abuse chains or partial mitigations already in place. Track, and resolve as part of your normal hardening cadence.
Confirmed
Observed directly by Jiffy scanners or validated by multiple independent sources. Indicators are reliable enough to drive automated action.
Indicators
Observed patterns and artifacts associated with this entry. Each indicator can be copied into your detection stack or SIEM.
https?://[a-z0-9.-]+(?:\.attacker|\.proxy-relay|-mitm\.)
Detection rule
A YARA-style pseudo-rule auto-generated from the indicators above. Useful as a starting point — adapt the syntax for your target detection platform.
rule jiffy_ti_2026_000049
{
meta:
source = "jiffy-intel"
severity = "medium"
description = "Auto-generated from Jiffy Intel indicators"
strings:
$endpoint_0 = "https?://[a-z0-9.-]+(?:\\.attacker|\\.proxy-relay|-mitm\\.)"
condition:
$endpoint_0
}Auto-generated from the indicators above. Adapt syntax for your detection stack before deploying.
Affected tools
| Tool | Versions | Status |
|---|---|---|
| Any MCP-capable agent | * | vulnerable |
Example artifacts
Sanitized examples of artifacts Jiffy has observed exhibiting this pattern. Publisher handles are redacted; version ranges and status reflect the most recent scan.
- search-helper-mcpMCP serverRemoved
- query-relay-mcpMCP serverUnder review
How to remediate
- 01Run MCP network traces against a known-good reference.
- 02Jiffy dynamic analysis tags unexpected hops.
Timeline & sources
Timeline
- First observedMar 7, 20261 month ago
- Last updatedApr 22, 2026today
- PublishedMar 19, 202629 days ago
Sources
References
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