T09 · Insecure Skill Coding Practices
- Location
scripts/tournament.sh:10- Finding
Unsafe JSON Construction from User-Controlled Agent Name
- Content
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Vulnerability Details
File Location:
scripts/tournament.sh, lines 10-14
Vulnerability Type: JSON payload injection caused by unsafe string interpolation
Risk Level: LowVulnerable Code
bash register) read -p "Agent name: " NAME curl -s -X POST "$API_BASE/register" \ -H "Content-Type: application/json" \ -d "{\"name\": \"$NAME\", \"ref\": \"ref_27fcab61\"}" | python3 -m json.tool ;;Technical Analysis
The script reads an agent name from standard input and inserts it directly into a JSON string without JSON-aware escaping. Characters such as double quotes, backslashes, and control characters can invalidate the request or change its logical structure.
Shell command injection is not established because the expansion of
NAMEoccurs inside a quoted shell argument. However, the quoting does not protect the JSON document itself. A crafted name can introduce additional properties if the resulting payload is accepted by the remote registration service.For example, an input similar to:
text x", "role": "admin", "unused": "would cause the generated request body to contain attacker-controlled JSON structure rather than treating the entire input solely as an agent name. The actual server-side effect depends on how strictly the remote API validates and filters registration properties.
Attack Path
- An attacker or untrusted caller invokes
bash scripts/tournament.sh register. - The caller supplies an agent name containing JSON syntax, including quotes and additional properties.
- The script interpolates the value into the
curl -dargument without JSON encoding. - The altered payload is transmitted to
https://agent.rollhub.com/api/v1/register. - If the service accepts unexpected or duplicate fields, the attacker may manipulate registration attributes beyond the intended
namevalue.
This path does not grant local shell execution, filesystem acc ...[truncated 611 chars]
- An attacker or untrusted caller invokes
- Remediation
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Remediation Suggestions
Construct the request body with a JSON serializer rather than manual string interpolation:
bash payload="$( python3 -c 'import json, sys; print(json.dumps({ "name": sys.argv[1], "ref": "ref_27fcab61" }))' "$NAME" )" curl -sS -X POST "$API_BASE/register" \ -H "Content-Type: application/json" \ --data-binary "$payload" | python3 -m json.toolAdditionally:
- Enforce a reasonable length limit and documented character policy for agent names.
- Reject control characters before sending the request.
- Use
curl --fail-with-bodyso HTTP failures are surfaced reliably. - Require the server to allowlist registration fields and reject unknown or duplicate properties.
- Do not rely on client-side validation as the API's only security boundary.