T09 · Insecure Skill Coding Practices
Warning
- Location
SKILL.md:233- Finding
Steam API Key Exposed in Command-Line URLs
- Content
View full analysis
- Remediation
View remediation
Security audit
Steamcommunity
Security checks for vulnerabilities and agentic risk
Overview
The skill is coherent for Steam inventory and trade management, but it asks users to handle live Steam credentials and perform item-transfer actions without enough safety guidance.
Install only if you are comfortable giving the agent access to your Steam session cookies and API key. Treat those values like passwords, avoid logging or sharing commands that contain them, verify every partner ID and asset ID manually, and require an explicit preview before sending or accepting any trade.
Vulnerability Patterns
- Insecure Skill Coding PracticesFinds exploitable flaws such as hardcoded secrets or command injection
- Skill Instruction HijackingAlters the agent's session goals or safety constraints when the skill loads
- Agent Memory PoisoningWrites attacker-controlled rules into memory that affect later sessions
- Remote Payload Retrieval and ExecutionFetches external code whose behavior can change after review
- Embedded Malicious CodeShips malicious scripts inside the skill and executes them locally
Findings (1)
Vulnerability Patterns
- Data ExfiltrationExternal Transmission, Env Variable Harvesting, File System Enumeration
- Prompt InjectionInstruction Override, Hidden Instructions, Exfiltration Commands
- Privilege EscalationExcessive Permissions, Sudo/Root Execution, Credential Access
- Supply ChainUnpinned Dependencies, External Script Fetching, Obfuscated Code
- Excessive AgencyUnrestricted Tool Access, Autonomous Decision Making, Scope Creep
Findings (15)
Missing User Warnings
Medium
- Category
- Not specified by scanner
- Confidence
- 98% confidence
- Finding
The setup instructs users to extract and store Steam session cookies, session IDs, and API keys without clear warnings that these are highly sensitive authentication secrets. Exposure of these values can let anyone impersonate the user for inventory access and trade actions, potentially leading to account abuse and item theft.
- Content
Missing User Warnings
Medium
- Category
- Not specified by scanner
- Confidence
- 96% confidence
- Finding
The skill documents high-risk trade actions including sending, accepting, canceling, and declining offers, but it does not prominently warn that these actions can irreversibly transfer valuable virtual items or cause permanent loss if the wrong offer is accepted or sent. In an agent context, omission of explicit confirmation and consequence warnings increases the chance of accidental destructive actions with real monetary value.
- Content
External Transmission
Medium
- Category
- Data Exfiltration
- Confidence
- 95% confidence
- Finding
This command transmits authenticated Steam session cookies and a trade token to Steam in order to create a trade offer, which can directly move items of real-world value. In an agent workflow, any mistaken parameter substitution, prompt injection, or unauthorized execution could result in fraudulent trades or asset loss.
- Content
md }' # Send with trade token (non-friend) curl -s "https://steamcommunity.com/tradeoffer/new/send" \ -X POST \ -H "Cookie: sessionid=$STEAM_SESSION_ID; $STEAM_COOKIES" \ -H "Referer: https://steamcommunity.com/tradeoffer/new/?partner=$PARTNER_ACCOUNT_ID&token=$TRADE_TOKEN" \
External Transmission
Medium
- Category
- Data Exfiltration
- Confidence
- 95% confidence
- Finding
This variant sends an authenticated trade offer to a friend using live session credentials, enabling direct transfer of inventory items. Because it performs a state-changing external action with account authority, misuse or automation errors can cause irreversible loss even without a trade token.
- Content
To send to a friend (no token needed), omit the
tokenfrom the Referer and settrade_offer_create_paramsto{}:bash curl -s "https://steamcommunity.com/tradeoffer/new/send" \ -X POST \ -H "Cookie: sessionid=$STEAM_SESSION_ID; $STEAM_COOKIES" \ -H "Referer: https://steamcommunity.com/tradeoffer/new/?partner=$PARTNER_ACCOUNT_ID" \
External Transmission
Medium
- Category
- Data Exfiltration
- Confidence
- 50% confidence
- Finding
Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.
- Content
bash # Get all active trade offers (sent and received) curl -s "https://api.steampowered.com/IEconService/GetTradeOffers/v1/?key=$STEAM_API_KEY&get_sent_offers=1&get_received_offers=1&active_only=1&get_descriptions=1&language=english" \ | jq '.'
External Transmission
Medium
- Category
- Data Exfiltration
- Confidence
- 50% confidence
- Finding
Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.
- Content
bash # Get all active trade offers (sent and received) curl -s "https://api.steampowered.com/IEconService/GetTradeOffers/v1/?key=$STEAM_API_KEY&get_sent_offers=1&get_received_offers=1&active_only=1&get_descriptions=1&language=english" \ | jq '.'
External Transmission
Medium
- Category
- Data Exfiltration
- Confidence
- 50% confidence
- Finding
Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.
- Content
bash # Get all active trade offers (sent and received) curl -s "https://api.steampowered.com/IEconService/GetTradeOffers/v1/?key=$STEAM_API_KEY&get_sent_offers=1&get_received_offers=1&active_only=1&get_descriptions=1&language=english" \ | jq '.'
External Transmission
Medium
- Category
- Data Exfiltration
- Confidence
- 50% confidence
- Finding
Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.
- Content
bash # Get all active trade offers (sent and received) curl -s "https://api.steampowered.com/IEconService/GetTradeOffers/v1/?key=$STEAM_API_KEY&get_sent_offers=1&get_received_offers=1&active_only=1&get_descriptions=1&language=english" \ | jq '.'
External Transmission
Medium
- Category
- Data Exfiltration
- Confidence
- 50% confidence
- Finding
Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.
- Content
bash # Get all active trade offers (sent and received) curl -s "https://api.steampowered.com/IEconService/GetTradeOffers/v1/?key=$STEAM_API_KEY&get_sent_offers=1&get_received_offers=1&active_only=1&get_descriptions=1&language=english" \ | jq '.'
External Transmission
Medium
- Category
- Data Exfiltration
- Confidence
- 50% confidence
- Finding
Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.
- Content
bash # Get all active trade offers (sent and received) curl -s "https://api.steampowered.com/IEconService/GetTradeOffers/v1/?key=$STEAM_API_KEY&get_sent_offers=1&get_received_offers=1&active_only=1&get_descriptions=1&language=english" \ | jq '.'
External Transmission
Medium
- Category
- Data Exfiltration
- Confidence
- 50% confidence
- Finding
Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.
- Content
bash # Get all active trade offers (sent and received) curl -s "https://api.steampowered.com/IEconService/GetTradeOffers/v1/?key=$STEAM_API_KEY&get_sent_offers=1&get_received_offers=1&active_only=1&get_descriptions=1&language=english" \ | jq '.'
External Transmission
Medium
- Category
- Data Exfiltration
- Confidence
- 50% confidence
- Finding
Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.
- Content
bash # Get all active trade offers (sent and received) curl -s "https://api.steampowered.com/IEconService/GetTradeOffers/v1/?key=$STEAM_API_KEY&get_sent_offers=1&get_received_offers=1&active_only=1&get_descriptions=1&language=english" \ | jq '.'
External Transmission
Medium
- Category
- Data Exfiltration
- Confidence
- 95% confidence
- Finding
The accept-offer request uses authenticated cookies to finalize a pending trade, which may permanently exchange items once confirmed. This is dangerous because accepting the wrong tradeofferid or a manipulated offer can immediately authorize unwanted asset transfer.
- Content
md TRADE_OFFER_ID="1234567890" PARTNER_STEAM_ID="76561198012345678" curl -s "https://steamcommunity.com/tradeoffer/$TRADE_OFFER_ID/accept" \ -X POST \ -H "Cookie: sessionid=$STEAM_SESSION_ID; $STEAM_COOKIES" \ -H "Referer: https://steamcommunity.com/tradeoffer/$TRADE_OFFER_ID/" \
External Transmission
Medium
- Category
- Data Exfiltration
- Confidence
- 60% confidence
- Finding
Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.
- Content
Cancel a sent trade offer
bash curl -s "https://api.steampowered.com/IEconService/CancelTradeOffer/v1/" \ -X POST \ -d "key=$STEAM_API_KEY" \ -d "tradeofferid=$TRADE_OFFER_ID"
Natural-Language Policy Violations
Low
- Category
- Not specified by scanner
- Confidence
- 96% confidence
- Finding
Across multiple examples, the skill forces English locale in request parameters, which is a natural-language policy concern when no opt-in or alternative is provided. The file does not explain why English is required or mention that users may substitute another language.
- Content
Static analysis
No suspicious patterns detected.