Incorrectly Specified Destination in a Communication Channel

The software creates a communication channel to initiate an outgoing request to an actor, but it does not correctly specify the intended destination for that actor.


Description

Attackers at the destination may be able to spoof trusted servers to steal data or cause a denial of service.

There are at least two distinct weaknesses that can cause the software to communicate with an unintended destination:

If the software allows an attacker to control which destination is specified, then the attacker can cause it to connect to an untrusted or malicious destination. For example, because UDP is a connectionless protocol, UDP packets can be spoofed by specifying a false source address in the packet; when the server receives the packet and sends a reply, it will specify a destination by using the source of the incoming packet - i.e., the false source. The server can then be tricked into sending traffic to the wrong host, which is effective for hiding the real source of an attack and for conducting a distributed denial of service (DDoS). As another example, server-side request forgery (SSRF) and XML External Entity (XXE) can be used to trick a server into making outgoing requests to hosts that cannot be directly accessed by the attacker due to firewall restrictions.

If the software incorrectly specifies the destination, then an attacker who can control this destination might be able to spoof trusted servers. While the most common occurrence is likely due to misconfiguration by an administrator, this can be resultant from other weaknesses. For example, the software might incorrectly parse an e-mail or IP address and send sensitive data to an unintended destination. As another example, an Android application may use a "sticky broadcast" to communicate with a receiver for a particular application, but since sticky broadcasts can be processed by *any* receiver, this can allow a malicious application to access restricted data that was only intended for a different application.

Demonstrations

The following examples help to illustrate the nature of this weakness and describe methods or techniques which can be used to mitigate the risk.

Note that the examples here are by no means exhaustive and any given weakness may have many subtle varieties, each of which may require different detection methods or runtime controls.

Example One

This code listens on a port for DNS requests and sends the result to the requesting address.

sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
sock.bind( (UDP_IP,UDP_PORT) )
while true:

  data = sock.recvfrom(1024)
  if not data:
    break

  (requestIP, nameToResolve) = parseUDPpacket(data)
  record = resolveName(nameToResolve)
  sendResponse(requestIP,record)

This code sends a DNS record to a requesting IP address. UDP allows the source IP address to be easily changed ('spoofed'), thus allowing an attacker to redirect responses to a target, which may be then be overwhelmed by the network traffic.

See Also

Identify Actors

Weaknesses in this category are related to the design and architecture of a system's identification management components. Frequently these deal with verifying that ex...

Communication Channel Errors

Weaknesses in this category are related to improper handling of communication channels and access paths. These weaknesses include problems in creating, managing, or re...

Comprehensive CWE Dictionary

This view (slice) covers all the elements in CWE.

Weaknesses without Software Fault Patterns

CWE identifiers in this view are weaknesses that do not have associated Software Fault Patterns (SFPs), as covered by the CWE-888 view. As such, they represent gaps in...

Weaknesses in Mobile Applications

CWE entries in this view (slice) are often seen in mobile applications.


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