---
title: Prevent shell injection
description: Datadog, the leading service for cloud-scale monitoring.
breadcrumbs: >-
  Docs > Datadog Security > Code Security > Static Code Analysis (SAST) > SAST
  Rules > Prevent shell injection
---

# Prevent shell injection

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## Metadata{% #metadata %}

**ID:** `csharp-security/shell-injection`

**Language:** C#

**Severity:** Warning

**Category:** Security

**CWE**: [78](https://cwe.mitre.org/data/definitions/78.html)

## Description{% #description %}

Never build a command to execute manually by concatenating strings. Instead, validate each component of the command to ensure there is no user-input.

#### Learn More{% #learn-more %}

- [CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')](https://cwe.mitre.org/data/definitions/78)

## Non-Compliant Code Examples{% #non-compliant-code-examples %}

```csharp
public class Sample
{
    public void myMethod(string myProgram)
    {
        Process p = new Process();
        p.StartInfo.FileName = "path/to/" + myProgram;
        p.Start();
    }
}

public class Runner {
    public static int Run(string cmd, string args, string input) {
        ProcessStartInfo startInfo = new ProcessStartInfo
        {
            WorkingDirectory = Settings.RootDir,
            FileName = cmd,
            Arguments = args,
            UseShellExecute = false,
            RedirectStandardInput = true,
            RedirectStandardError = true,
            RedirectStandardOutput = true,
        };
        using (Process process = new Process())
        {
            process.EnableRaisingEvents = true;
            process.StartInfo = startInfo;
            process.Start();
        }
    }
}
```

## Compliant Code Examples{% #compliant-code-examples %}

```csharp
public class Sample
{
    public void myMethod()
    {
        // Safe: using hardcoded command path
        Process p = new Process();
        p.StartInfo.FileName = "path/to/program";
        p.Start();
    }
}
```
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