When creating commands using interpolation into a string, developers may assume that only the arguments/options that they specify will be processed. This assumption may be even stronger when the programmer has encoded the command in a way that prevents separate commands from being provided maliciously, e.g. in the case of shell metacharacters. When constructing the command, the developer may use whitespace or other delimiters that are required to separate arguments when the command. However, if an attacker can provide an untrusted input that contains argument-separating delimiters, then the resulting command will have more arguments than intended by the developer. The attacker may then be able to change the behavior of the command. Depending on the functionality supported by the extraneous arguments, this may have security-relevant consequences.
| Impact | Details |
|---|---|
|
Execute Unauthorized Code or Commands; Alter Execution Logic; Read Application Data; Modify Application Data |
Scope: Confidentiality, Integrity, Availability, Other
An attacker could include arguments that allow unintended commands or code to be executed, allow sensitive data to be read or modified or could cause other unintended behavior.
|
| Phase(s) | Mitigation |
|---|---|
|
Implementation |
Strategy: Parameterization Where possible, avoid building a single string that contains the command and its arguments. Some languages or frameworks have functions that support specifying independent arguments, e.g. as an array, which is used to automatically perform the appropriate quoting or escaping while building the command. For example, in PHP, escapeshellarg() can be used to escape a single argument to system(), or exec() can be called with an array of arguments. In C, code can often be refactored from using system() - which accepts a single string - to using exec(), which requires separate function arguments for each parameter.
Effectiveness: High |
|
Architecture and Design |
Strategy: Input Validation Understand all the potential areas where untrusted inputs can enter your product: parameters or arguments, cookies, anything read from the network, environment variables, request headers as well as content, URL components, e-mail, files, databases, and any external systems that provide data to the application. Perform input validation at well-defined interfaces.
|
|
Implementation |
Strategy: Input Validation 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 |
Directly convert your input type into the expected data type, such as using a conversion function that translates a string into a number. After converting to the expected data type, ensure that the input's values fall within the expected range of allowable values and that multi-field consistencies are maintained.
|
|
Implementation |
Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180, CWE-181). Make sure that your application does not inadvertently decode the same input twice (CWE-174). Such errors could be used to bypass allowlist schemes by introducing dangerous inputs after they have been checked. Use libraries such as the OWASP ESAPI Canonicalization control. Consider performing repeated canonicalization until your input does not change any more. This will avoid double-decoding and similar scenarios, but it might inadvertently modify inputs that are allowed to contain properly-encoded dangerous content. |
|
Implementation |
When exchanging data between components, ensure that both components are using the same character encoding. Ensure that the proper encoding is applied at each interface. Explicitly set the encoding you are using whenever the protocol allows you to do so.
|
|
Implementation |
When your application combines data from multiple sources, perform the validation after the sources have been combined. The individual data elements may pass the validation step but violate the intended restrictions after they have been combined.
|
|
Testing |
Use automated static analysis tools that target this type of weakness. Many modern techniques use data flow analysis to minimize the number of false positives. This is not a perfect solution, since 100% accuracy and coverage are not feasible.
|
|
Testing |
Use dynamic tools and techniques that interact with the product using large test suites with many diverse inputs, such as fuzz testing (fuzzing), robustness testing, and fault injection. The product's operation may slow down, but it should not become unstable, crash, or generate incorrect results.
|
| Nature | Type | ID | Name |
|---|---|---|---|
| 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. | 77 | Improper Neutralization of Special Elements used in a Command ('Command Injection') |
| Nature | Type | ID | Name |
|---|---|---|---|
| MemberOf | Category Category - a CWE entry that contains a set of other entries that share a common characteristic. | 137 | Data Neutralization Issues |
| Nature | Type | ID | Name |
|---|---|---|---|
| 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. | 74 | Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection') |
| Nature | Type | ID | Name |
|---|---|---|---|
| MemberOf | Category Category - a CWE entry that contains a set of other entries that share a common characteristic. | 1019 | Validate Inputs |
| Nature | Type | ID | Name |
|---|---|---|---|
| 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. | 77 | Improper Neutralization of Special Elements used in a Command ('Command Injection') |
| Nature | Type | ID | Name |
|---|---|---|---|
| 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. | 77 | Improper Neutralization of Special Elements used in a Command ('Command Injection') |
| Phase | Note |
|---|---|
| Implementation | REALIZATION: This weakness is caused during implementation of an architectural security tactic. |
Class: Not Language-Specific (Undetermined Prevalence)
PHP (Often Prevalent)
Example 1
Consider the following program. It intends to perform an "ls -l" on an input filename. The validate_name() subroutine performs validation on the input to make sure that only alphanumeric and "-" characters are allowed, which avoids path traversal (CWE-22) and OS command injection (CWE-78) weaknesses. Only filenames like "abc" or "d-e-f" are intended to be allowed.
However, validate_name() allows filenames that begin with a "-". An adversary could supply a filename like "-aR", producing the "ls -l -aR" command (CWE-88), thereby getting a full recursive listing of the entire directory and all of its sub-directories.
There are a couple possible mitigations for this weakness. One would be to refactor the code to avoid using system() altogether, instead relying on internal functions.
Another option could be to add a "--" argument to the ls command, such as "ls -l --", so that any remaining arguments are treated as filenames, causing any leading "-" to be treated as part of a filename instead of another option.
Another fix might be to change the regular expression used in validate_name to force the first character of the filename to be a letter or number, such as:
Example 2
CVE-2016-10033 / [REF-1249] provides a useful real-world example of this weakness within PHPMailer.
The program calls PHP's mail() function to compose and send mail. The fifth argument to mail() is a set of parameters. The program intends to provide a "-fSENDER" parameter, where SENDER is expected to be a well-formed email address. The program has already validated the e-mail address before invoking mail(), but there is a lot of flexibility in what constitutes a well-formed email address, including whitespace. With some additional allowed characters to perform some escaping, the adversary can specify an additional "-o" argument (listing an output file) and a "-X" argument (giving a program to execute). Additional details for this kind of exploit are in [REF-1250].
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 |
|---|---|
|
Python-based dependency management tool avoids OS command injection when generating Git commands but allows injection of optional arguments with input beginning with a dash (CWE-88), potentially allowing for code execution.
|
|
|
Canonical Example - "-froot" argument is passed on to another program, where the "-f" causes execution as user "root"
|
|
|
Web browser executes Telnet sessions using command line arguments that are specified by the web site, which could allow remote attackers to execute arbitrary commands.
|
|
|
Web browser allows remote attackers to execute commands by spawning Telnet with a log file option on the command line and writing arbitrary code into an executable file which is later executed.
|
|
|
Argument injection vulnerability in the mail function for PHP may allow attackers to bypass safe mode restrictions and modify command line arguments to the MTA (e.g. sendmail) possibly executing commands.
|
|
|
Help and Support center in windows does not properly validate HCP URLs, which allows remote attackers to execute arbitrary code via quotation marks in an "hcp://" URL.
|
|
|
Mail client does not sufficiently filter parameters of mailto: URLs when using them as arguments to mail executable, which allows remote attackers to execute arbitrary programs.
|
|
|
Web browser doesn't filter "-" when invoking various commands, allowing command-line switches to be specified.
|
|
|
Mail client allows remote attackers to execute arbitrary code via a URI that uses a UNC network share pathname to provide an alternate configuration file.
|
|
|
SSH URI handler for web browser allows remote attackers to execute arbitrary code or conduct port forwarding via the a command line option.
|
|
|
Web browser doesn't filter "-" when invoking various commands, allowing command-line switches to be specified.
|
|
|
Argument injection vulnerability in TellMe 1.2 and earlier allows remote attackers to modify command line arguments for the Whois program and obtain sensitive information via "--" style options in the q_Host parameter.
|
|
|
Beagle before 0.2.5 can produce certain insecure command lines to launch external helper applications while indexing, which allows attackers to execute arbitrary commands. NOTE: it is not immediately clear whether this issue involves argument injection, shell metacharacters, or other issues.
|
|
|
Argument injection vulnerability in Internet Explorer 6 for Windows XP SP2 allows user-assisted remote attackers to modify command line arguments to an invoked mail client via " (double quote) characters in a mailto: scheme handler, as demonstrated by launching Microsoft Outlook with an arbitrary filename as an attachment. NOTE: it is not clear whether this issue is implementation-specific or a problem in the Microsoft API.
|
|
|
Argument injection vulnerability in Mozilla Firefox 1.0.6 allows user-assisted remote attackers to modify command line arguments to an invoked mail client via " (double quote) characters in a mailto: scheme handler, as demonstrated by launching Microsoft Outlook with an arbitrary filename as an attachment. NOTE: it is not clear whether this issue is implementation-specific or a problem in the Microsoft API.
|
|
|
Argument injection vulnerability in Avant Browser 10.1 Build 17 allows user-assisted remote attackers to modify command line arguments to an invoked mail client via " (double quote) characters in a mailto: scheme handler, as demonstrated by launching Microsoft Outlook with an arbitrary filename as an attachment. NOTE: it is not clear whether this issue is implementation-specific or a problem in the Microsoft API.
|
|
|
Argument injection vulnerability in the URI handler in Skype 2.0.*.104 and 2.5.*.0 through 2.5.*.78 for Windows allows remote authorized attackers to download arbitrary files via a URL that contains certain command-line switches.
|
|
|
Argument injection vulnerability in WinSCP 3.8.1 build 328 allows remote attackers to upload or download arbitrary files via encoded spaces and double-quote characters in a scp or sftp URI.
|
|
|
Argument injection vulnerability in the Windows Object Packager (packager.exe) in Microsoft Windows XP SP1 and SP2 and Server 2003 SP1 and earlier allows remote user-assisted attackers to execute arbitrary commands via a crafted file with a "/" (slash) character in the filename of the Command Line property, followed by a valid file extension, which causes the command before the slash to be executed, aka "Object Packager Dialogue Spoofing Vulnerability."
|
|
|
Argument injection vulnerability in HyperAccess 8.4 allows user-assisted remote attackers to execute arbitrary vbscript and commands via the /r option in a telnet:// URI, which is configured to use hawin32.exe.
|
|
|
Argument injection vulnerability in the telnet daemon (in.telnetd) in Solaris 10 and 11 (SunOS 5.10 and 5.11) misinterprets certain client "-f" sequences as valid requests for the login program to skip authentication, which allows remote attackers to log into certain accounts, as demonstrated by the bin account.
|
|
|
Argument injection allows execution of arbitrary commands by injecting a "-exec" option, which is executed by the command.
|
|
|
Argument injection in mail-processing function allows writing unxpected files and executing programs using tecnically-valid email addresses that insert "-o" and "-X" switches.
|
| Ordinality | Description |
|---|---|
|
Primary
|
(where the weakness exists independent of other weaknesses)
|
| Method | Details |
|---|---|
|
Automated Static Analysis |
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.)
Effectiveness: High |
| Nature | Type | ID | Name |
|---|---|---|---|
| MemberOf | CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. | 741 | CERT C Secure Coding Standard (2008) Chapter 8 - Characters and Strings (STR) |
| MemberOf | CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. | 744 | CERT C Secure Coding Standard (2008) Chapter 11 - Environment (ENV) |
| MemberOf | CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. | 810 | OWASP Top Ten 2010 Category A1 - Injection |
| MemberOf | CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. | 875 | CERT C++ Secure Coding Section 07 - Characters and Strings (STR) |
| MemberOf | CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. | 878 | CERT C++ Secure Coding Section 10 - Environment (ENV) |
| MemberOf | ViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries). | 884 | CWE Cross-section |
| MemberOf | CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. | 929 | OWASP Top Ten 2013 Category A1 - Injection |
| MemberOf | CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. | 990 | SFP Secondary Cluster: Tainted Input to Command |
| MemberOf | CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. | 1027 | OWASP Top Ten 2017 Category A1 - Injection |
| MemberOf | CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. | 1165 | SEI CERT C Coding Standard - Guidelines 10. Environment (ENV) |
| MemberOf | CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. | 1347 | OWASP Top Ten 2021 Category A03:2021 - Injection |
| MemberOf | CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. | 1409 | Comprehensive Categorization: Injection |
Rationale
This CWE entry is at the Base 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.Relationship
| Mapped Taxonomy Name | Node ID | Fit | Mapped Node Name |
|---|---|---|---|
| PLOVER | Argument Injection or Modification | ||
| CERT C Secure Coding | ENV03-C | Sanitize the environment when invoking external programs | |
| CERT C Secure Coding | ENV33-C | Imprecise | Do not call system() |
| CERT C Secure Coding | STR02-C | Sanitize data passed to complex subsystems | |
| WASC | 30 | Mail Command Injection |
| Submissions | |||
|---|---|---|---|
| Submission Date | Submitter | Organization | |
|
2006年07月19日
(CWE Draft 3, 2006年07月19日) |
PLOVER | ||
| Contributions | |||
| Contribution Date | Contributor | Organization | |
| 2021年05月28日 | Anonymous External Contributor | ||
| Identified inappropriate demonstrative example, suggested new observed example, applicable language. | |||
| Modifications | |||
| Modification Date | Modifier | Organization | |
|
2025年09月09日
(CWE 4.18, 2025年09月09日) |
CWE Content Team | MITRE | |
| updated Functional_Areas | |||
|
2024年07月16日
(CWE 4.15, 2024年07月16日) |
CWE Content Team | MITRE | |
| updated Observed_Examples | |||
| 2023年06月29日 | CWE Content Team | MITRE | |
| updated Mapping_Notes | |||
| 2023年04月27日 | CWE Content Team | MITRE | |
| updated Description, Detection_Factors, References, Relationships, Time_of_Introduction | |||
| 2023年01月31日 | CWE Content Team | MITRE | |
| updated Description, Potential_Mitigations | |||
| 2022年10月13日 | CWE Content Team | MITRE | |
| updated Observed_Examples | |||
| 2022年04月28日 | CWE Content Team | MITRE | |
| updated Applicable_Platforms, Demonstrative_Examples, Observed_Examples, References | |||
| 2021年10月28日 | CWE Content Team | MITRE | |
| updated Relationships | |||
| 2020年12月10日 | CWE Content Team | MITRE | |
| updated Relationships | |||
| 2020年08月20日 | CWE Content Team | MITRE | |
| updated Relationships | |||
| 2020年06月25日 | CWE Content Team | MITRE | |
| updated Potential_Mitigations | |||
| 2020年02月24日 | CWE Content Team | MITRE | |
| updated Potential_Mitigations, Relationships | |||
| 2019年09月23日 | CWE Content Team | MITRE | |
| updated Description, Name, Observed_Examples, Potential_Mitigations | |||
| 2019年09月19日 | CWE Content Team | MITRE | |
| updated Description, Name, References, Relationships | |||
| 2019年06月20日 | CWE Content Team | MITRE | |
| updated Related_Attack_Patterns, Relationships | |||
| 2019年01月03日 | CWE Content Team | MITRE | |
| updated Relationships | |||
| 2018年03月27日 | CWE Content Team | MITRE | |
| updated Relationships | |||
| 2017年11月08日 | CWE Content Team | MITRE | |
| updated Applicable_Platforms, Causal_Nature, Modes_of_Introduction, Relationships, Taxonomy_Mappings | |||
| 2015年12月07日 | CWE Content Team | MITRE | |
| updated Demonstrative_Examples, Relationships | |||
| 2014年07月30日 | CWE Content Team | MITRE | |
| updated Relationships | |||
| 2014年06月23日 | CWE Content Team | MITRE | |
| updated Relationships | |||
| 2012年10月30日 | CWE Content Team | MITRE | |
| updated Potential_Mitigations | |||
| 2012年05月11日 | CWE Content Team | MITRE | |
| updated Common_Consequences, Demonstrative_Examples, Observed_Examples, References, Related_Attack_Patterns, Relationships | |||
| 2011年09月13日 | CWE Content Team | MITRE | |
| updated Relationships, Taxonomy_Mappings | |||
| 2011年06月01日 | CWE Content Team | MITRE | |
| updated Common_Consequences | |||
| 2010年09月27日 | CWE Content Team | MITRE | |
| updated Relationships | |||
| 2010年06月21日 | CWE Content Team | MITRE | |
| updated Observed_Examples, Relationships | |||
| 2010年04月05日 | CWE Content Team | MITRE | |
| updated Related_Attack_Patterns | |||
| 2010年02月16日 | CWE Content Team | MITRE | |
| updated Potential_Mitigations, Relationships, Taxonomy_Mappings | |||
| 2009年10月29日 | CWE Content Team | MITRE | |
| updated Observed_Examples | |||
| 2009年07月27日 | CWE Content Team | MITRE | |
| updated Other_Notes, Relationship_Notes | |||
| 2008年11月24日 | CWE Content Team | MITRE | |
| updated Observed_Examples, Relationships, Taxonomy_Mappings | |||
| 2008年09月08日 | CWE Content Team | MITRE | |
| updated Relationships, Other_Notes, Taxonomy_Mappings, Weakness_Ordinalities | |||
| 2008年07月01日 | Eric Dalci | Cigital | |
| updated Time_of_Introduction | |||
| Previous Entry Names | |||
| Change Date | Previous Entry Name | ||
| 2019年09月19日 | Argument Injection or Modification | ||
| 2019年09月23日 | Improper Delimitation of Arguments in a Command ('Argument Injection') | ||
Use of the Common Weakness Enumeration (CWE™) and the associated references from this website are subject to the Terms of Use. CWE is sponsored by the U.S. Department of Homeland Security (DHS) Cybersecurity and Infrastructure Security Agency (CISA) and managed by the Homeland Security Systems Engineering and Development Institute (HSSEDI) which is operated by The MITRE Corporation (MITRE). Copyright © 2006–2025, The MITRE Corporation. CWE, CWSS, CWRAF, and the CWE logo are trademarks of The MITRE Corporation.