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Home > CWE List > CWE-291: Reliance on IP Address for Authentication (4.18)
ID
CWE Glossary Definition

CWE-291: Reliance on IP Address for Authentication

Weakness ID: 291
Vulnerability Mapping: ALLOWED This CWE ID may be used to map to real-world vulnerabilities
Abstraction: Variant Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.
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Description
The product uses an IP address for authentication.
Extended Description
IP addresses can be easily spoofed. Attackers can 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.
Common Consequences
Section HelpThis table specifies different individual consequences associated with the weakness. The Scope identifies the application security area that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in exploiting this weakness. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a weakness will be exploited to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.
Impact Details

Hide Activities; Gain Privileges or Assume Identity

Scope: Access Control, Non-Repudiation

Malicious users can fake authentication information, impersonating any IP address.
Potential Mitigations
Phase(s) Mitigation

Architecture and Design
Use other means of identity verification that cannot be simply spoofed. Possibilities include a username/password or certificate.
Relationships
Section Help This table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
Relevant to the view "Research Concepts" (View-1000)
Nature Type ID Name
ChildOf Base Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource. 290 Authentication Bypass by Spoofing
ChildOf Class Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource. 923 Improper Restriction of Communication Channel to Intended Endpoints
Relevant to the view "Architectural Concepts" (View-1008)
Nature Type ID Name
MemberOf Category Category - a CWE entry that contains a set of other entries that share a common characteristic. 1010 Authenticate Actors
Modes Of Introduction
Section HelpThe different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.
Phase Note
Architecture and Design COMMISSION: This weakness refers to an incorrect design related to an architectural security tactic.
Applicable Platforms
Section HelpThis listing shows possible areas for which the given weakness could appear. These may be for specific named Languages, Operating Systems, Architectures, Paradigms, Technologies, or a class of such platforms. The platform is listed along with how frequently the given weakness appears for that instance.
Languages

Class: Not Language-Specific (Undetermined Prevalence)

Likelihood Of Exploit
High
Demonstrative Examples

Example 1


Both of these examples check if a request is from a trusted address before responding to the request.

(bad code)
Example Language: C
sd = socket(AF_INET, SOCK_DGRAM, 0);
serv.sin_family = AF_INET;
serv.sin_addr.s_addr = htonl(INADDR_ANY);
servr.sin_port = htons(1008);
bind(sd, (struct sockaddr *) & serv, sizeof(serv));

while (1) {
memset(msg, 0x0, MAX_MSG);
clilen = sizeof(cli);
if (inet_ntoa(cli.sin_addr)==getTrustedAddress()) {
n = recvfrom(sd, msg, MAX_MSG, 0, (struct sockaddr *) & cli, &clilen);
}
}
(bad code)
Example Language: Java
while(true) {
DatagramPacket rp=new DatagramPacket(rData,rData.length);
outSock.receive(rp);
String in = new String(p.getData(),0, rp.getLength());
InetAddress clientIPAddress = rp.getAddress();
int port = rp.getPort();

if (isTrustedAddress(clientIPAddress) & secretKey.equals(in)) {
out = secret.getBytes();
DatagramPacket sp =new DatagramPacket(out,out.length, IPAddress, port); outSock.send(sp);
}
}

The code only verifies the address as stored in the request packet. An attacker can spoof this address, thus impersonating a trusted client.



Selected Observed Examples

Note: this is a curated list of examples for users to understand the variety of ways in which this weakness can be introduced. It is not a complete list of all CVEs that are related to this CWE entry.

Reference Description
S-bus functionality in a home automation product performs access control using an IP allowlist, which can be bypassed by a forged IP address.
Weakness Ordinalities
Ordinality Description
Resultant
(where the weakness is typically related to the presence of some other weaknesses)
Memberships
Section HelpThis MemberOf Relationships table shows additional CWE Categories and Views that reference this weakness as a member. This information is often useful in understanding where a weakness fits within the context of external information sources.
Nature Type ID Name
MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 1396 Comprehensive Categorization: Access Control
Vulnerability Mapping Notes
Usage ALLOWED
(this CWE ID may be used to map to real-world vulnerabilities)
Reason Acceptable-Use

Rationale

This CWE entry is at the Variant level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.

Comments

Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.
Taxonomy Mappings
Mapped Taxonomy Name Node ID Fit Mapped Node Name
CLASP Trusting self-reported IP address
References
[REF-18] Secure Software, Inc.. "The CLASP Application Security Process". 2005.
<https://cwe.mitre.org/documents/sources/TheCLASPApplicationSecurityProcess.pdf>. (URL validated: 2024年11月17日)
[REF-1371] "IP address spoofing". Wikipedia. 2006年04月07日.
<https://en.wikipedia.org/wiki/IP_address_spoofing>. (URL validated: 2023年10月21日)
Content History
Submissions
Submission Date Submitter Organization
2006年07月19日
(CWE Draft 3, 2006年07月19日) 		CLASP
Modifications
Modification Date Modifier Organization
2025年04月03日
(CWE 4.17, 2025年04月03日) 		CWE Content Team MITRE
updated Relationships
2023年10月26日 CWE Content Team MITRE
updated Observed_Examples, References
2023年06月29日 CWE Content Team MITRE
updated Mapping_Notes
2023年04月27日 CWE Content Team MITRE
updated Relationships
2023年01月31日 CWE Content Team MITRE
updated Description
2020年02月24日 CWE Content Team MITRE
updated References, Relationships
2017年11月08日 CWE Content Team MITRE
updated Causal_Nature, Demonstrative_Examples, Modes_of_Introduction, Relationships
2014年02月18日 CWE Content Team MITRE
updated Relationships
2013年07月17日 CWE Content Team MITRE
updated Applicable_Platforms, Description, Name, Relationships, Type
2013年06月23日 CWE Content Team MITRE
Changed type from composite to weakness.
2012年05月11日 CWE Content Team MITRE
updated Demonstrative_Examples, Relationships
2011年06月01日 CWE Content Team MITRE
updated Common_Consequences, Demonstrative_Examples
2010年02月16日 CWE Content Team MITRE
updated Description, Other_Notes
2008年09月08日 CWE Content Team MITRE
updated Common_Consequences, Relationships, Other_Notes, Taxonomy_Mappings, Weakness_Ordinalities
Previous Entry Names
Change Date Previous Entry Name
2013年07月17日 Trusting Self-reported IP Address
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Page Last Updated: September 09, 2025

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