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Security audit

Dropbox Sign

Security checks for vulnerabilities and agentic risk

Overview

The Dropbox Sign reads fit the stated purpose, but setup can execute unchecked installation code and introduce undisclosed changes to agent skills.

Review and approve CLI installation separately, verify a fixed release, and consider disabling automatic skill synchronization with OO_SKILLS_SYNC_DISABLED=1. Connect only the account needed for your reads and understand that OOMOL brokers access to its private records. The external installer and server-side connector implementation were not verified.

Vulnerability Patterns
  • 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
  • Unauthorized Access and Privilege EscalationObtains permissions beyond the task's legitimate needs
Vulnerability Patterns
  • Supply ChainUnpinned Dependencies, External Script Fetching, Obfuscated Code
  • Excessive AgencyUnrestricted Tool Access, Autonomous Decision Making, Scope Creep
  • Output HandlingUnvalidated Output Injection, Cross-Context Output, Unbounded Output
  • MCP Tool PoisoningHidden Instructions, Unicode Deception, Parameter Description Injection
  • Prompt InjectionInstruction Override, Hidden Instructions, Exfiltration Commands
Findings (4)

Description-Behavior Mismatch

High
Category
MCP Tool Poisoning
Confidence
99% confidence
Finding

The supplied command performs remote code execution for an installer, not Dropbox Sign searching or reading. Nothing in the supplied chunk establishes that this installation is a supporting dependency for Dropbox Sign, and the downloaded script's further behavior cannot be determined from this code.

Content

No source excerpt is available for this finding.

External Script Fetching

High
Category
Supply Chain
Confidence
98% confidence
Finding

The command pipes a mutable remote script directly into Bash without pinning or verifying its contents; the PowerShell alternative has the same execution pattern. If the distribution endpoint or publishing pipeline is compromised, attacker-controlled code could run with the agent's local privileges and access files or credentials. HTTPS and the legitimate CLI dependency reduce some concerns but do not establish script integrity.

Content

Scanner excerpt · SKILL.md (reported line 59)May include surrounding context.

Fallback setup executes downloaded installation scripts without warning about local system changes.

Medium
Category
Output Handling
Confidence
93% confidence
Finding

The fallback instructs the agent to install software when the CLI is missing without first explaining local changes or obtaining installation-specific approval. A request to read Dropbox Sign data does not itself authorize executing an installer on the user's machine, although the missing-command prerequisite limits when this behavior occurs.

Content

No source excerpt is available for this finding.

Autonomous Decision Making

Medium
Category
Excessive Agency
Confidence
80% confidence
Finding

Skill enables autonomous high-impact decisions without human-in-the-loop verification. Critical operations (destructive commands, financial transactions, data deletion) should require explicit user confirmation.

Content

Scanner excerpt · SKILL.md (reported line 80)May include surrounding context.

md
- **`OOMOL_INSUFFICIENT_CREDIT`** — OOMOL billing stop. Recharge at `https://console.oomol.com/billing/token-recharge` before retrying.

- **HTTP 402 without `OOMOL_INSUFFICIENT_CREDIT`** — the third-party account itself has no active plan or credit. Report the provider error message as is; do not ask the user to recharge OOMOL.

## Resources