Compromised McpPublished Mar 19, 2026

MCP server redirects tool results through attacker proxy

MediumAARM tierConfirmed
Seen17times across4customers
jiffy-ti-2026-000049

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

Severity
Medium

Medium

Notable weakness with plausible abuse chains or partial mitigations already in place. Track, and resolve as part of your normal hardening cadence.

Confidence
Confirmed

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.

YARA-style pseudo-rule
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

ToolVersionsStatus
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 server
    Removed
    Source
    MCP Registry
    Versions
    0.5.0
    First observed
    Mar 7, 2026
    Last observed
    Apr 2, 2026
  • query-relay-mcpMCP server
    Under review
    Source
    Community registry
    First observed
    Mar 11, 2026

How to remediate

  1. 01Run MCP network traces against a known-good reference.
  2. 02Jiffy dynamic analysis tags unexpected hops.

Timeline & sources

Timeline

  1. First observedMar 7, 20261 month ago
  2. Last updatedApr 22, 2026today
  3. PublishedMar 19, 202629 days ago

Sources

curated

References

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