Run static analysis (SAST) on the codebase looking for the unsafe pattern in the data flow.
CWE-428 Base Draft
Unquoted Search Path or Element
This vulnerability occurs when a program uses a file path or command that contains spaces and is not enclosed in quotes. The operating system may misinterpret where the executable file is located,…
Definition
What is CWE-428?
This vulnerability occurs when a program uses a file path or command that contains spaces and is not enclosed in quotes. The operating system may misinterpret where the executable file is located, potentially allowing an attacker to run a malicious program with higher privileges.
When a path like `C:\Program Files\MyApp\app.exe` is called without quotes, the system interprets each space as a separator between arguments. It will first try to execute `C:\Program.exe`, then `C:\Program Files\MyApp\app.exe`. If an attacker can place a malicious file named `Program.exe` in the root directory (C:\), the system will run that file instead of the intended application.
This is a classic privilege escalation path on Windows systems. If a high-privileged service or user runs a program with an unquoted path, an attacker with write access to a parent directory (like C:\) can plant a malicious executable with a name that matches an earlier segment of the path. The system's search order then executes the attacker's file with the same elevated permissions.
Real-world impact
Real-world CVEs caused by CWE-428
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Small handful of others. Program doesn't quote the "C:\Program Files\" path when calling a program to be executed - or any other path with a directory or file whose name contains a space - so attacker can put a malicious program.exe into C:.
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CreateProcess() and CreateProcessAsUser() can be misused by applications to allow "program.exe" style attacks in C:
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Applies to "Common Files" folder, with a malicious common.exe, instead of "Program Files"/program.exe.
How attackers exploit it
Step-by-step attacker path
- 1
Identify a code path that handles untrusted input without validation.
- 2
Craft a payload that exercises the unsafe behavior — injection, traversal, overflow, or logic abuse.
- 3
Deliver the payload through a normal request and observe the application's reaction.
- 4
Iterate until the response leaks data, executes attacker code, or escalates privileges.
Vulnerable code example
Vulnerable C
The following example demonstrates the weakness.
UINT errCode = WinExec( "C:\\Program Files\\Foo\\Bar", SW_SHOW ); 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-428
- Implementation Properly quote the full search path before executing a program on the system.
- Implementation Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue." Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
- Implementation Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked.
Detection signals
How to detect CWE-428
Run dynamic application security testing against the live endpoint.
Watch runtime logs for unusual exception traces, malformed input, or authorization bypass attempts.
Code review: flag any new code that handles input from this surface without using the validated framework helpers.
Plexicus auto-detects CWE-428 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-428?
How serious is CWE-428?
What languages or platforms are affected by CWE-428?
How can I prevent CWE-428?
How does Plexicus detect and fix CWE-428?
Where can I learn more about CWE-428?
Frequently asked questions
What is CWE-428?
This vulnerability occurs when a program uses a file path or command that contains spaces and is not enclosed in quotes. The operating system may misinterpret where the executable file is located, potentially allowing an attacker to run a malicious program with higher privileges.
How serious is CWE-428?
MITRE has not published a likelihood-of-exploit rating for this weakness. Treat it as medium-impact until your threat model proves otherwise.
What languages or platforms are affected by CWE-428?
MITRE lists the following affected platforms: Windows NT, macOS.
How can I prevent CWE-428?
Properly quote the full search path before executing a program on the system. Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable…
How does Plexicus detect and fix CWE-428?
Plexicus's SAST engine matches the data-flow signature for CWE-428 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-428?
MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/428.html. You can also reference OWASP and NIST documentation for adjacent guidance.
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