Automated static analysis is useful for detecting certain types of authentication. A tool may be able to analyze related configuration files, such as .htaccess in Apache web servers, or detect the usage of commonly-used authentication libraries. Generally, automated static analysis tools have difficulty detecting custom authentication schemes. In addition, the software's design may include some functionality that is accessible to any user and does not require an established identity; an automated technique that detects the absence of authentication may report false positives.
CWE-287 Class Draft
Improper Authentication
Improper Authentication occurs when a system fails to properly verify a user's claimed identity, allowing access without sufficient proof of who they are.
Definition
What is CWE-287?
Improper Authentication occurs when a system fails to properly verify a user's claimed identity, allowing access without sufficient proof of who they are.
This vulnerability happens when an application doesn't implement strong enough checks to confirm a user is who they say they are. Attackers can exploit weak or missing authentication to impersonate legitimate users, gain unauthorized access, and steal sensitive data or perform privileged actions. Common causes include skipping authentication entirely, using weak credential checks, or accidentally leaving debug backdoors active.
To prevent this, developers must implement robust, standardized authentication mechanisms for all access points. This includes using strong password policies, multi-factor authentication (MFA), secure session management, and ensuring authentication logic cannot be bypassed. Always validate credentials against a trusted authority and treat any unauthenticated request as originating from an anonymous, untrusted user.
Real-world impact
Real-world CVEs caused by CWE-287
-
File-sharing PHP product does not check if user is logged in during requests for PHP library files under an includes/ directory, allowing configuration changes, code execution, and other impacts.
-
Chat application skips validation when Central Authentication Service (CAS) is enabled, effectively removing the second factor from two-factor authentication
-
Python-based authentication proxy does not enforce password authentication during the initial handshake, allowing the client to bypass authentication by specifying a 'None' authentication type.
-
Chain: Web UI for a Python RPC framework does not use regex anchors to validate user login emails (CWE-777), potentially allowing bypass of OAuth (CWE-1390).
-
TCP-based protocol in Programmable Logic Controller (PLC) has no authentication.
-
Condition Monitor uses a protocol that does not require authentication.
-
Safety Instrumented System uses proprietary TCP protocols with no authentication.
-
Distributed Control System (DCS) uses a protocol that has no authentication.
How attackers exploit it
Step-by-step attacker path
- 1
The following code intends to ensure that the user is already logged in. If not, the code performs authentication with the user-provided username and password. If successful, it sets the loggedin and user cookies to "remember" that the user has already logged in. Finally, the code performs administrator tasks if the logged-in user has the "Administrator" username, as recorded in the user cookie.
- 2
Unfortunately, this code can be bypassed. The attacker can set the cookies independently so that the code does not check the username and password. The attacker could do this with an HTTP request containing headers such as:
- 3
By setting the loggedin cookie to "true", the attacker bypasses the entire authentication check. By using the "Administrator" value in the user cookie, the attacker also gains privileges to administer the software.
- 4
In January 2009, an attacker was able to gain administrator access to a Twitter server because the server did not restrict the number of login attempts [REF-236]. The attacker targeted a member of Twitter's support team and was able to successfully guess the member's password using a brute force attack by guessing a large number of common words. After gaining access as the member of the support staff, the attacker used the administrator panel to gain access to 33 accounts that belonged to celebrities and politicians. Ultimately, fake Twitter messages were sent that appeared to come from the compromised accounts.
- 5
In 2022, the OT:ICEFALL study examined products by 10 different Operational Technology (OT) vendors. The researchers reported 56 vulnerabilities and said that the products were "insecure by design" [REF-1283]. If exploited, these vulnerabilities often allowed adversaries to change how the products operated, ranging from denial of service to changing the code that the products executed. Since these products were often used in industries such as power, electrical, water, and others, there could even be safety implications.
Vulnerable code example
Vulnerable Perl
The following code intends to ensure that the user is already logged in. If not, the code performs authentication with the user-provided username and password. If successful, it sets the loggedin and user cookies to "remember" that the user has already logged in. Finally, the code performs administrator tasks if the logged-in user has the "Administrator" username, as recorded in the user cookie.
my $q = new CGI;
if ($q->cookie('loggedin') ne "true") {
if (! AuthenticateUser($q->param('username'), $q->param('password'))) {
ExitError("Error: you need to log in first");
}
else {
# Set loggedin and user cookies.
$q->cookie(
-name => 'loggedin',
-value => 'true'
);
$q->cookie(
-name => 'user',
-value => $q->param('username')
);
}
}
if ($q->cookie('user') eq "Administrator") {
DoAdministratorTasks();
} Attacker payload
Unfortunately, this code can be bypassed. The attacker can set the cookies independently so that the code does not check the username and password. The attacker could do this with an HTTP request containing headers such as:
GET /cgi-bin/vulnerable.cgi HTTP/1.1
Cookie: user=Administrator
Cookie: loggedin=true
[body of request] Secure code example
Secure pseudo
// Validate, sanitize, or use a safe API before reaching the sink.
function handleRequest(input) {
const safe = validateAndEscape(input);
return executeWithGuards(safe);
} What changed: the unsafe sink is replaced (or the input is validated/escaped) so the same payload no longer triggers the weakness.
Prevention checklist
How to prevent CWE-287
- Architecture and Design Use an authentication framework or library such as the OWASP ESAPI Authentication feature.
Detection signals
How to detect CWE-287
This weakness can be detected using tools and techniques that require manual (human) analysis, such as penetration testing, threat modeling, and interactive tools that allow the tester to record and modify an active session. Manual static analysis is useful for evaluating the correctness of custom authentication mechanisms.
According to SOAR [REF-1479], the following detection techniques may be useful: ``` Cost effective for partial coverage: ``` Binary / Bytecode disassembler - then use manual analysis for vulnerabilities & anomalies
According to SOAR [REF-1479], the following detection techniques may be useful: ``` Cost effective for partial coverage: ``` Web Application Scanner Web Services Scanner Database Scanners
According to SOAR [REF-1479], the following detection techniques may be useful: ``` Cost effective for partial coverage: ``` Fuzz Tester Framework-based Fuzzer
According to SOAR [REF-1479], the following detection techniques may be useful: ``` Cost effective for partial coverage: ``` Manual Source Code Review (not inspections)
Plexicus auto-detects CWE-287 and opens a fix PR in under 60 seconds.
Codex Remedium scans every commit, identifies this exact weakness, and ships a reviewer-ready pull request with the patch. No tickets. No hand-offs.
Frequently asked questions What is CWE-287?
How serious is CWE-287?
What languages or platforms are affected by CWE-287?
How can I prevent CWE-287?
How does Plexicus detect and fix CWE-287?
Where can I learn more about CWE-287?
Frequently asked questions
What is CWE-287?
Improper Authentication occurs when a system fails to properly verify a user's claimed identity, allowing access without sufficient proof of who they are.
How serious is CWE-287?
MITRE rates the likelihood of exploit as High — this weakness is actively exploited in the wild and should be prioritized for remediation.
What languages or platforms are affected by CWE-287?
MITRE lists the following affected platforms: ICS/OT.
How can I prevent CWE-287?
Use an authentication framework or library such as the OWASP ESAPI Authentication feature.
How does Plexicus detect and fix CWE-287?
Plexicus's SAST engine matches the data-flow signature for CWE-287 on every commit. When a match is found, our Codex Remedium agent opens a fix PR with the corrected code, tests, and a one-line summary for the reviewer.
Where can I learn more about CWE-287?
MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/287.html. You can also reference OWASP and NIST documentation for adjacent guidance.
Related weaknesses
Weaknesses related to CWE-287
CWE-284 Parent
Improper Access Control
The software fails to properly limit who can access a resource, allowing unauthorized users or systems to interact with it.
CWE-1191 Sibling
On-Chip Debug and Test Interface With Improper Access Control
This vulnerability occurs when a hardware chip's debug or test interface (like JTAG) lacks proper access controls. Without correct…
CWE-1220 Sibling
Insufficient Granularity of Access Control
This vulnerability occurs when a system's access controls are too broad, allowing unauthorized users or processes to read or modify…
CWE-1224 Sibling
Improper Restriction of Write-Once Bit Fields
This vulnerability occurs when hardware write-once protection mechanisms, often called 'sticky bits,' are incorrectly implemented,…
CWE-1231 Sibling
Improper Prevention of Lock Bit Modification
This vulnerability occurs when hardware or firmware uses a lock bit to protect critical system registers or memory regions, but fails to…
CWE-1233 Sibling
Security-Sensitive Hardware Controls with Missing Lock Bit Protection
This vulnerability occurs when a hardware device uses a lock bit to protect critical configuration registers, but the lock fails to…
CWE-1252 Sibling
CPU Hardware Not Configured to Support Exclusivity of Write and Execute Operations
This vulnerability occurs when a CPU's hardware is not set up to enforce a strict separation between writing data to memory and executing…
CWE-1257 Sibling
Improper Access Control Applied to Mirrored or Aliased Memory Regions
This vulnerability occurs when a hardware design maps the same physical memory to multiple addresses (aliasing or mirroring) but fails to…
CWE-1259 Sibling
Improper Restriction of Security Token Assignment
This vulnerability occurs when a System-on-a-Chip (SoC) fails to properly secure its Security Token mechanism. These tokens control which…
Resources
Further reading
- MITRE — official CWE-287 https://cwe.mitre.org/data/definitions/287.html
- Weak Password Brings 'Happiness' to Twitter Hacker https://www.wired.com/2009/01/professed-twitt/
- Top 10 2007-Broken Authentication and Session Management https://web.archive.org/web/20160319231145/http://www.owasp.org/index.php/Top_10_2007-A7
- Guide to Authentication http://www.owasp.org/index.php/Guide_to_Authentication
- Authentication http://msdn.microsoft.com/en-us/library/aa374735(VS.85).aspx
- Writing Secure Code https://www.microsoftpressstore.com/store/writing-secure-code-9780735617223
- OT:ICEFALL: The legacy of "insecure by design" and its implications for certifications and risk management https://www.forescout.com/resources/ot-icefall-report/
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