To protect against command injection, avoid interacting with an operating system (OS) dynamically.

Before processing the user's input, take these three important steps to validate it into consideration:

• Sanitize early
• Escape Late
• Always Validate

User input can come from forms, HTTP headers, cookies, or URL parameters. In cases where this input is used to set parameters to OS-level commands, use the following guidelines for setting firewall rules, configuring service settings, or configuring network interfaces:

• Determine what kind of user input is acceptable.
• Limit acceptable characters strictly.

For example, if your application dynamically starts a user-specified process through shell interaction and it needs user-supplied parameters as dynamic input to the process:

Consider an application that starts a shell interaction process by the user. If the process needs user-generated settings as dynamic input, use the following guidelines:

• Only allow specific process names and reject all others character combinations.
• Only allow the very limited required special characters for the input parameters.

  - `A-Z`, `a-z`, `0-9`, `.`, and `@`.
  

Use built-in APIs instead of generic "exec.Command()" (Go)

Limit using exec.Command() as much as possible, especially if you are executing a binary whose name is coming from a user input. Instead, try to use specific built-in APIs.

In the following example, we use exec.Command() to run chmod command.

The example for non-compliant code:

**`
//A bad example that should be avoided
package main

import "fmt"
import "os/exec"
import "os"

func main()

if err := exec.Command("bash", "-c", "chmod 664 file").Run(); err != nil

}
**`

In the second example we demonstrate how to use an equivalent built-in API (os.Chmod()).

The example for compliant code:

**`
//An example of specific APIs
if err := os.Chmod(file, 664); err != nil {
fmt.Fprintln(os.Stderr, err)
os.Exit(1)
}
**`

Imported from SD Elements: https://redhat.sdelements.com/bunits/psse-secure-development/group-2-extended-functionality-offerings/openshift-source-to-image-s2i-builder-image/tasks/phase/development/106-T43/