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.
CWE-259 Variant Draft
Use of Hard-coded Password
This vulnerability occurs when an application embeds a password directly into its source code or configuration files. This hard-coded secret is then used either to authenticate incoming users or to…
Definition
What is CWE-259?
This vulnerability occurs when an application embeds a password directly into its source code or configuration files. This hard-coded secret is then used either to authenticate incoming users or to connect to external services and databases.
Hard-coded passwords create two major security risks. First, for inbound authentication, anyone with access to the code can discover the password and gain unauthorized access. Second, for outbound connections, the embedded credentials for databases, APIs, or other services cannot be changed without modifying and redeploying the application, making rotation and management nearly impossible. Both scenarios bypass standard secret management and leave the system permanently exposed if the code is ever leaked or shared.
To fix this, always store passwords, API keys, and other secrets in secure, external management systems like environment variables, vaults, or dedicated secret managers. This allows for secure access control, auditing, and easy rotation without code changes. While SAST tools can detect the hard-coded pattern, Plexicus uses AI to analyze the context and suggest the correct remediation—such as replacing the static string with a secure fetch from a vault—saving developers hours of manual refactoring and reducing the risk of misconfiguration.
Real-world impact
Real-world CVEs caused by CWE-259
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Distributed Control System (DCS) has hard-coded passwords for local shell access
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Telnet service for IoT feeder for dogs and cats has hard-coded password [REF-1288]
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Firmware for a WiFi router uses a hard-coded password for a BusyBox shell, allowing bypass of authentication through the UART port
How attackers exploit it
Step-by-step attacker path
- 1
The following code uses a hard-coded password to connect to a database:
- 2
This is an example of an external hard-coded password on the client-side of a connection. This code will run successfully, but anyone who has access to it will have access to the password. Once the program has shipped, there is no going back from the database user "scott" with a password of "tiger" unless the program is patched. A devious employee with access to this information can use it to break into the system. Even worse, if attackers have access to the bytecode for application, they can use the javap -c command to access the disassembled code, which will contain the values of the passwords used. The result of this operation might look something like the following for the example above:
- 3
The following code is an example of an internal hard-coded password in the back-end:
- 4
Every instance of this program can be placed into diagnostic mode with the same password. Even worse is the fact that if this program is distributed as a binary-only distribution, it is very difficult to change that password or disable this "functionality."
- 5
The following examples show a portion of properties and configuration files for Java and ASP.NET applications. The files include username and password information but they are stored in cleartext.
Vulnerable code example
Vulnerable Java
The following code uses a hard-coded password to connect to a database:
...
DriverManager.getConnection(url, "scott", "tiger");
... Attacker payload
This is an example of an external hard-coded password on the client-side of a connection. This code will run successfully, but anyone who has access to it will have access to the password. Once the program has shipped, there is no going back from the database user "scott" with a password of "tiger" unless the program is patched. A devious employee with access to this information can use it to break into the system. Even worse, if attackers have access to the bytecode for application, they can use the javap -c command to access the disassembled code, which will contain the values of the passwords used. The result of this operation might look something like the following for the example above:
javap -c ConnMngr.class
22: ldc #36; //String jdbc:mysql://ixne.com/rxsql
24: ldc #38; //String scott
26: ldc #17; //String tiger 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-259
- Architecture and Design For outbound authentication: store passwords outside of the code in a strongly-protected, encrypted configuration file or database that is protected from access by all outsiders, including other local users on the same system. Properly protect the key (CWE-320). If you cannot use encryption to protect the file, then make sure that the permissions are as restrictive as possible.
- Architecture and Design For inbound authentication: Rather than hard-code a default username and password for first time logins, utilize a "first login" mode that requires the user to enter a unique strong password.
- Architecture and Design Perform access control checks and limit which entities can access the feature that requires the hard-coded password. For example, a feature might only be enabled through the system console instead of through a network connection.
- Architecture and Design For inbound authentication: apply strong one-way hashes to your passwords and store those hashes in a configuration file or database with appropriate access control. That way, theft of the file/database still requires the attacker to try to crack the password. When receiving an incoming password during authentication, take the hash of the password and compare it to the hash that you have saved. Use randomly assigned salts for each separate hash that you generate. This increases the amount of computation that an attacker needs to conduct a brute-force attack, possibly limiting the effectiveness of the rainbow table method.
- Architecture and Design For front-end to back-end connections: Three solutions are possible, although none are complete. ``` The first suggestion involves the use of generated passwords which are changed automatically and must be entered at given time intervals by a system administrator. These passwords will be held in memory and only be valid for the time intervals. Next, the passwords used should be limited at the back end to only performing actions valid for the front end, as opposed to having full access. Finally, the messages sent should be tagged and checksummed with time sensitive values so as to prevent replay style attacks. ```
Detection signals
How to detect CWE-259
Use monitoring tools that examine the software's process as it interacts with the operating system and the network. This technique is useful in cases when source code is unavailable, if the software was not developed by you, or if you want to verify that the build phase did not introduce any new weaknesses. Examples include debuggers that directly attach to the running process; system-call tracing utilities such as truss (Solaris) and strace (Linux); system activity monitors such as FileMon, RegMon, Process Monitor, and other Sysinternals utilities (Windows); and sniffers and protocol analyzers that monitor network traffic. Attach the monitor to the process and perform a login. Using disassembled code, look at the associated instructions and see if any of them appear to be comparing the input to a fixed string or value.
Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)
Plexicus auto-detects CWE-259 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-259?
How serious is CWE-259?
What languages or platforms are affected by CWE-259?
How can I prevent CWE-259?
How does Plexicus detect and fix CWE-259?
Where can I learn more about CWE-259?
Frequently asked questions
What is CWE-259?
This vulnerability occurs when an application embeds a password directly into its source code or configuration files. This hard-coded secret is then used either to authenticate incoming users or to connect to external services and databases.
How serious is CWE-259?
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-259?
MITRE lists the following affected platforms: ICS/OT.
How can I prevent CWE-259?
For outbound authentication: store passwords outside of the code in a strongly-protected, encrypted configuration file or database that is protected from access by all outsiders, including other local users on the same system. Properly protect the key (CWE-320). If you cannot use encryption to protect the file, then make sure that the permissions are as restrictive as possible. For inbound authentication: Rather than hard-code a default username and password for first time logins, utilize a…
How does Plexicus detect and fix CWE-259?
Plexicus's SAST engine matches the data-flow signature for CWE-259 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-259?
MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/259.html. You can also reference OWASP and NIST documentation for adjacent guidance.
Related weaknesses
Weaknesses related to CWE-259
CWE-798 Parent
Use of Hard-coded Credentials
This vulnerability occurs when software contains built-in, unchangeable authentication secrets like passwords or encryption keys within…
CWE-321 Sibling
Use of Hard-coded Cryptographic Key
This vulnerability occurs when an application embeds a fixed, unchangeable cryptographic key directly within its source code or…
CWE-257 Peer
Storing Passwords in a Recoverable Format
This vulnerability occurs when an application stores user passwords in a format that can be easily reversed or decrypted back to their…
Resources
Further reading
- MITRE — official CWE-259 https://cwe.mitre.org/data/definitions/259.html
- Seven Pernicious Kingdoms: A Taxonomy of Software Security Errors https://samate.nist.gov/SSATTM_Content/papers/Seven%20Pernicious%20Kingdoms%20-%20Taxonomy%20of%20Sw%20Security%20Errors%20-%20Tsipenyuk%20-%20Chess%20-%20McGraw.pdf
- OT:ICEFALL: The legacy of "insecure by design" and its implications for certifications and risk management https://www.forescout.com/resources/ot-icefall-report/
- Ethical hacking of a Smart Automatic Feed Dispenser http://kth.diva-portal.org/smash/get/diva2:1561552/FULLTEXT01.pdf
- ICS Alert (ICS-ALERT-13-164-01): Medical Devices Hard-Coded Passwords https://www.cisa.gov/news-events/ics-alerts/ics-alert-13-164-01
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