postboi@0.54.3
Postboi is an email provider and TypeScript SDK. Send email with one token and no DNS setup, plus SMS, WhatsApp, push and chat from the same API. You can also use your own provider (Resend, SES, Postmark and more) if you want to.
AI Security Review
scanned 1mo ago · by lpm-firewall-aiThis is first-party agent-skill setup from an explicit CLI command, and init --agent auto-accepts the write into .claude, .agents, and AGENTS.md. It is not an unconsented npm install hook or a hidden payload.
Static reason
High-risk behavior combination matched malicious policy.; previous stored version diff introduced dangerous source
Trigger
A user or coding agent runs postboi init, postboi init --agent, or postboi skill.
Impact
Project agent instructions are changed so later coding agents load Postboi's skill. The change is limited to this package's own skill files and an AGENTS.md pointer.
Mechanism
offer_skill and skill_command copy the bundled skill into .claude and .agents and, when AGENTS.md exists and does not already mention postboi, append a pointer. The --agent prompt helper returns true for confirm.
AI rationale
This is first-party agent-skill setup from an explicit CLI command, and init --agent auto-accepts the write into .claude, .agents, and AGENTS.md. It is not an unconsented npm install hook or a hidden payload.
Evidence
package.jsondist/cli.js.claude/skills/postboi/SKILL.md.agents/skills/postboi/SKILL.mdAGENTS.md
Decision evidence
public snapshotAI called this Suspicious at 84.0% confidence as Dangerous Capability with medium false-positive risk.
Evidence for warning
- package.json ships a postboi bin at dist/cli.js and has no preinstall, install, or postinstall hook.
- The CLI writes a first-party agent skill to .claude/skills/postboi/SKILL.md, copies it to .agents/skills/postboi/SKILL.md, and appends a Postboi pointer to AGENTS.md.
- postboi init --agent treats every confirm prompt as accepted, so offer_skill installs those files without an interactive yes.
- If the Claude skill file is already present, a later init refreshes it and the companion files without asking again. The skill subcommand installs them directly.
Evidence against
- Registry install does not run a lifecycle hook that edits agent files.
- A normal postboi init asks before the first skill install.
- The bundled skill is documentation for this mail SDK, not a downloaded executable payload.
Behavioral surface
ChildProcessCryptoDynamicRequireEnvironmentVarsFilesystemNetworkShell
Source & flagged code
7 flaggeddist/cli.jsView file
41// src/library/encoding.ts
L42: function base64_decode(value) {
L43: const binary = atob(value);
...
L125: const { pathToFileURL } = await import("node:url");
L126: let dir = process.cwd();
L127: for (;; ) {
...
L270: if (this.#hooks.before?.send) {
L271: return this.#hooks.before.send({
L272: provider: this.provider,
...
L319: async send_request(url, init) {
L320: return fetch(url, init);
L321: }
Critical
Credential Exfiltration
Source appears to send environment or credential material to an external endpoint.
dist/cli.jsView on unpkg · L4141// src/library/encoding.ts
L42: function base64_decode(value) {
L43: const binary = atob(value);
...
L125: const { pathToFileURL } = await import("node:url");
L126: let dir = process.cwd();
L127: for (;; ) {
...
L270: if (this.#hooks.before?.send) {
L271: return this.#hooks.before.send({
L272: provider: this.provider,
...
L319: async send_request(url, init) {
L320: return fetch(url, init);
L321: }
Critical
Browser Credential Phishing
Source appears to collect browser login credentials for exfiltration.
dist/cli.jsView on unpkg · L41•matchType = previous_version_dangerous_delta
matchedPackage = postboi@0.51.0
matchedIdentity = npm:cG9zdGJvaQ:0.51.0
similarity = 0.950
summary = stored previous version shares package body but lacks this dangerous source file
Findings
3 Critical3 High4 Medium5 Low
CriticalCredential Exfiltrationdist/cli.js
CriticalBrowser Credential Phishingdist/cli.js
CriticalPrevious Version Dangerous Deltadist/cli.js
HighChild Processdist/cli.js
HighShelldist/cli.js
HighCommand Output Exfiltrationdist/cli.js
MediumDynamic Requiredist/workers_env.js
MediumNetwork
MediumEnvironment Vars
MediumStructural Risk Force Deep Review
LowNon Install Lifecycle Scripts
LowScripts Present
LowFilesystem
LowHigh Entropy Strings
LowUrl Strings
Affected versions and remediation
This report applies to postboi@0.54.3.
See all versions of postboi for other recorded verdicts.
- Review the evidence and your use of postboi@0.54.3 before allowing it. Restrict the permissions described in this report.
- Choose an independently verified alternative or release. This report does not establish that other versions are safe.
Evidence last updated: .
Think this verdict is wrong? Dispute it on GitHub or read how reports are produced.