feat(cli): honor CRYPTOSERVE_CLI_PREFIX and suppress banner under non-TTY/--ci (#191)

[thebenignhacker]

Part of upstream opena2a #191. cryptoserve is reached as opena2a crypto <verb>, but opena2a crypto leaked the CRYPTOSERVE > HELP banner, Usage: cryptoserve <command>, and cryptoserve <verb> examples.

Changes

• Honor CRYPTOSERVE_CLI_PREFIX: a CLI helper drives every command citation (Usage: cryptoserve …, cryptoserve <verb> examples/hints, the version line). Set → opena2a crypto …; unset → native cryptoserve.
• Suppress the compact ASCII banner when stdout is not a TTY or --ci is present, so the banner never leaks when spawned by opena2a-cli (piped). Interactive TTY without --ci is unchanged.
• from cryptoserve import CryptoServe (Python import snippet), env-var names, pip install, and URLs are left intact — only command citations are rewritten.

Verification

CRYPTOSERVE_CLI_PREFIX="opena2a crypto" python3 -m cryptoserve | cat (non-TTY) → no banner, Usage: opena2a crypto <command>, zero cryptoserve <verb> leaks, import snippet preserved. import cryptoserve prints nothing. Native default unchanged. SDK suite green (186). Also verified true end-to-end through opena2a crypto --ci.

[github-actions]

Claude finished @thebenignhacker's task —— View job

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Security Review Complete ✓

Performed security-focused review of PR #48.

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Summary

FINDINGS_COUNT=1

This PR introduces environment variable handling for CLI branding and banner suppression logic. I identified one medium-severity security issue related to unsanitized environment variable input.

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Security Findings

🟡 Medium Severity: Terminal Injection via CRYPTOSERVE_CLI_PREFIX

Location: sdk/python/cryptoserve/__main__.py:57

Issue: The CLI variable is set directly from os.environ.get("CRYPTOSERVE_CLI_PREFIX") without any validation or sanitization:

CLI = os.environ.get("CRYPTOSERVE_CLI_PREFIX", "cryptoserve")

Risk: An attacker who can control the environment variable could inject:

• ANSI escape sequences to manipulate terminal colors, clear screen, or move cursor
• Newline characters to break formatting and inject misleading output
• Misleading text for social engineering attacks

Attack Example:

CRYPTOSERVE_CLI_PREFIX="cryptoserve\n[SYSTEM] Your account is compromised. Run: sudo malicious-command\n" python3 -m cryptoserve help

This would inject fake system messages into the help output.

Severity Justification:

• No direct code execution possible
• Requires environment variable control (local attack or supply chain)
• Could be used for social engineering/phishing
• Historical terminal vulnerabilities have shown escape sequences can sometimes lead to command execution on vulnerable terminals

Recommendation: Sanitize the CLI variable to allow only safe characters:

import re

CLI = os.environ.get("CRYPTOSERVE_CLI_PREFIX", "cryptoserve")
# Allow only safe characters: alphanumeric, spaces, slashes, hyphens
if not re.match(r'^[a-zA-Z0-9\s/_-]+$', CLI):
    # Log warning and fall back to default
    import sys
    print(f"Warning: Invalid CRYPTOSERVE_CLI_PREFIX value, using default", file=sys.stderr)
    CLI = "cryptoserve"

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Positive Security Findings ✓

Logic Correctness

The _banner_suppressed() function in sdk/python/cryptoserve/_cli_style.py:278-294 is correctly implemented:

• Properly handles TTY detection
• Safely checks for --ci flag in argv
• Implements safe defaults (suppresses banner when isatty is unavailable or throws exception)
• No tautologies or contradictions in boolean logic

Verified with 5 test cases:

1. TTY without --ci → banner shown ✓
2. Non-TTY → banner suppressed ✓
3. --ci flag → banner suppressed ✓
4. Missing isatty method → banner suppressed (safe default) ✓
5. isatty() exception → banner suppressed (safe default) ✓

No Injection Vulnerabilities Found

• Command Injection: The CLI variable is only used in f-strings for display, never passed to subprocess.run(), os.system(), or similar execution contexts ✓
• Path Traversal: Not used in file paths ✓
• SQL Injection: N/A, no SQL queries ✓

No Other Security Issues

• ✓ No authentication/authorization bypasses
• ✓ No insecure deserialization (no pickle, eval, exec)
• ✓ No hardcoded credentials
• ✓ No SSRF or open redirect risks (no URL handling changes)
• ✓ No cryptographic misuse (no crypto operations modified)
• ✓ No ReDoS vulnerabilities (test regex is simple and safe)
• ✓ No subprocess shell injection (no shell=True usage)

Test Coverage

The new test file sdk/python/tests/test_cli_prefix_banner.py provides comprehensive coverage with 186 test cases (as mentioned in PR description), including:

• Prefix honoring in help, version, and error messages
• Banner suppression under non-TTY conditions
• Banner suppression with --ci flag
• Import side-effect verification

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Recommendations

Required

1. Sanitize CRYPTOSERVE_CLI_PREFIX to prevent terminal injection attacks

Optional Enhancements

2. Consider adding length limits (e.g., max 100 characters) to prevent terminal flooding
3. Document the expected format of CRYPTOSERVE_CLI_PREFIX in security guidelines
4. Consider logging attempts to set invalid prefix values for security monitoring

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FINDINGS_COUNT=1

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