BindToAllInterfaces.ql

/**
 * @name Binding a socket to all network interfaces
 * @description Binding a socket to all interfaces opens it up to traffic from any IPv4 address
 * and is therefore associated with security risks.
 * @kind path-problem
 * @tags security
 *       external/cwe/cwe-200
 * @problem.severity error
 * @security-severity 6.5
 * @sub-severity low
 * @precision high
 * @id py/bind-socket-all-network-interfaces
 */

import python
import semmle.python.dataflow.new.DataFlow
import semmle.python.dataflow.new.TaintTracking
private import semmle.python.frameworks.data.ModelsAsData
import BindToAllInterfacesFlow::PathGraph

/** Gets a hostname that can be used to bind to all interfaces. */
private string vulnerableHostname() {
  result in [
      // IPv4
      "0.0.0.0", "",
      // IPv6
      "::", "::0"
    ]
}

private module BindToAllInterfacesConfig implements DataFlow::ConfigSig {
  predicate isSource(DataFlow::Node source) {
    source.asExpr().(StringLiteral).getText() = vulnerableHostname()
  }

  predicate isSink(DataFlow::Node sink) {
    ModelOutput::sinkNode(sink, "bind-socket-all-interfaces") and
    // Network socket addresses are tuples like (host, port), so we require
    // the bind() argument to originate from a tuple expression. This excludes
    // AF_UNIX sockets, which pass a plain string path to bind().
    any(DataFlow::LocalSourceNode n | n.asExpr() instanceof Tuple).flowsTo(sink)
  }
}

private module BindToAllInterfacesFlow = TaintTracking::Global<BindToAllInterfacesConfig>;

private import BindToAllInterfacesFlow

from PathNode source, PathNode sink
where flowPath(source, sink)
select sink.getNode(), source, sink,
  "Binding a socket to all interfaces (using $@) is a security risk.", source.getNode(),
  "'" + source.getNode().asExpr().(StringLiteral).getText() + "'"