Difference between revisions of "Often Misused: Authentication"

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==Related Attacks==
==Related Attacks==
[[:Category:API Abuse Attack]]
==Related Vulnerabilities==
==Related Vulnerabilities==
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[[Category:Authentication Vulnerability]]
[[Category:Authentication Vulnerability]]
[[Category:API Abuse]]
[[Category:Use of Dangerous API]]

Revision as of 12:05, 18 July 2006

This article includes content generously donated to OWASP by Fortify.JPG.

This is a Vulnerability. To view all vulnerabilities, please see the Vulnerability Category page.


Attackers can spoof DNS entries. Do not rely on DNS names for security.


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.


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;

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.

Related Threats

Related Attacks

Category:API Abuse Attack

Related Vulnerabilities

Related Countermeasures



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