Web Application Security Scanner von Google

Skipfish ist ein in C geschriebenes Kommandozeilen-Tool von Google. Es ermöglicht das Scannen von Webseiten, um mögliche Schwachstellen und Sicherheitslücken früh zu identifizieren. Es geht dabei relativ flott und trotzdem genau zu werke. Der normale Test dauert durchaus einige Stunden, arbeitet trotzdem mit bis zu 2.000 HTTP Anfragen pro Sekunde (dank purem C-Code). Die sehr umfangreiche Testsuite deckt eigentlich alle bekannten Sicherheitsmängel ab und versucht diese in einer Webapplikation zu finden.

Die Software* liegt nur als Quellcode vor und muss vor Gebrauch kompiliert werden, hier reicht ein einfaches make unter Linux etc. Falls Fehler auftreten: prüfen ob openssl installiert ist und ob die passenden devel-Pakete dazu vorliegen.

Ein umfangreicher Test prüft dabei auf folgende potentielle Schwachstellen:

• High risk flaws (potentially leading to system* compromise):
  • Server-side SQL injection (including blind vectors, numerical parameters).
  • Explicit SQL-like syntax in GET or POST parameters.
  • Server-side shell command injection (including blind vectors).
  • Server-side XML / XPath injection (including blind vectors).
  • Format string vulnerabilities.
  • Integer overflow vulnerabilities.

• Medium risk flaws (potentially leading to data compromise):
  • Stored and reflected XSS vectors in document body (minimal JS XSS support present).
  • Stored and reflected XSS vectors via HTTP redirects.
  • Stored and reflected XSS vectors via HTTP header splitting.
  • Directory traversal (including constrained vectors).
  • Assorted file POIs (server-side sources, configs, etc).
  • Attacker-supplied script and CSS inclusion vectors (stored and reflected).
  • External untrusted script and CSS inclusion vectors.
  • Mixed content problems on script and CSS resources (optional).
  • Incorrect or missing MIME types on renderables.
  • Generic MIME types on renderables.
  • Incorrect or missing charsets on renderables.
  • Conflicting MIME / charset info on renderables.
  • Bad caching directives on cookie setting responses.

• Low risk issues (limited impact or low specificity):
  • Directory listing bypass vectors.
  • Redirection to attacker-supplied URLs (stored and reflected).
  • Attacker-supplied embedded content (stored and reflected).
  • External untrusted embedded content.
  • Mixed content on non-scriptable subresources (optional).
  • HTTP credentials in URLs.
  • Expired or not-yet-valid SSL certificates.
  • HTML forms with no XSRF protection.
  • Self-signed SSL certificates.
  • SSL certificate host name mismatches.
  • Bad caching directives on less sensitive content.

• Internal warnings:
  • Failed resource fetch attempts.
  • Exceeded crawl limits.
  • Failed 404 behavior checks.
  • IPS filtering detected.
  • Unexpected response variations.
  • Seemingly misclassified crawl nodes.

• Non-specific informational entries:
  • General SSL certificate information.
  • Significantly changing HTTP cookies.
  • Changing Server, Via, or X-… headers.
  • New 404 signatures.
  • Resources that cannot be accessed.
  • Resources requiring HTTP authentication.
  • Broken links.
  • Server errors.
  • All external links not classified otherwise (optional).
  • All external e-mails (optional).
  • All external URL redirectors (optional).
  • Links to unknown protocols.
  • Form fields that could not be autocompleted.
  • All HTML forms detected.
  • Password entry forms (for external brute-force).
  • Numerical file names (for external brute-force).
  • User-supplied links otherwise rendered on a page.
  • Incorrect or missing MIME type on less significant content.
  • Generic MIME type on less significant content.
  • Incorrect or missing charset on less significant content.
  • Conflicting MIME / charset information on less significant content.
  • OGNL-like parameter passing conventions.