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CWE-247 Individual Dictionary Definition (Draft 9)
Weakness ID
| Status: Incomplete 247 (Weakness Variant) | | Description | Summary Attackers can spoof DNS entries. Do not rely on DNS names for security. | Demonstrative Examples | The following code sample uses a DNS lookup in order to decide whether or not an
inbound request is from a trusted host. If an attacker can poison the DNS cache, they can
gain trusted status. String ip = request.getRemoteAddr(); InetAddress addr = InetAddress.getByName(ip); if (addr.getCanonicalHostName().endsWith("trustme.com")) { trusted = true; } IPAddress hostIPAddress = IPAddress.Parse(RemoteIpAddress); IPHostEntry hostInfo = Dns.GetHostByAddress(hostIPAddress); if (hostInfo.HostName.EndsWith("trustme.com")) { trusted = true; } IP addresses are more reliable than DNS names, but they can also be spoofed.
Attackers can easily forge the source IP address of the packets they send, but response
packets will return to the forged IP address. To see the response packets, the attacker
has to sniff the traffic between the victim machine and the forged IP address. In order to
accomplish the required sniffing, attackers typically attempt to locate themselves on the
same subnet as the victim machine. Attackers may be able to circumvent this requirement by
using source routing, but source routing is disabled across much of the Internet today. In
summary, IP address verification can be a useful part of an authentication scheme, but it
should not be the single factor required for authentication. | | Context Notes | Many DNS servers are susceptible to spoofing attacks, so you should assume that your
software will someday run in an environment with a compromised DNS server. If attackers are
allowed to make DNS updates (sometimes called DNS cache poisoning), they can route your network
traffic through their machines or make it appear as if their IP addresses are part of your domain.
Do not base the security of your system on DNS names. | | Relationships | | | Source Taxonomies | 7 Pernicious Kingdoms - Often Misused: Authentication | | Applicable Platforms | All | | Related Attack Patterns | | CAPEC-ID | Attack Pattern Name |
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| 89 | Pharming |
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