Secure file deletion
import java.io.File
import java.nio.file.{Files, Paths}
def deleteFile(fileName: String) {
val file = new File(fileName)
if (file.exists()) {
file.delete()
}
}
The above Scala function
deleteFile()
takes a filename as input and deletes the file if it exists. This function uses the
java.io.File
class to handle file operations.
The vulnerability here is that the
delete()
method in the
java.io.File
class does not securely delete files. When a file is deleted using this method, it is typically moved to the Recycle Bin or Trash of the operating system, or the space it occupied on the disk is simply marked as available for reuse. This means that the file's data remains on the disk and can potentially be recovered using special software.
This is particularly problematic if the deleted files contain sensitive information, such as passwords, personal data, or confidential business information. If an attacker gains access to the system, they could potentially recover these "deleted" files and gain access to this sensitive information.
To fix this vulnerability, files must be securely deleted in a way that their data cannot be recovered. This often involves overwriting the file's data before it is deleted, sometimes multiple times, to ensure that the original data cannot be recovered.
import java.io.{File, FileOutputStream, RandomAccessFile}
import java.nio.file.{Files, Paths}
import java.security.SecureRandom
def secureDeleteFile(fileName: String) {
val file = new File(fileName)
if (file.exists()) {
val randomAccessFile = new RandomAccessFile(file, "rws")
val secureRandom = new SecureRandom()
val data = new Array[Byte](1024)
for(_ <- 1 to 10) { // overwrite file content 10 times
secureRandom.nextBytes(data)
randomAccessFile.write(data)
}
randomAccessFile.close()
file.delete()
}
}
The above code securely deletes a file in a Scala backend application that uses the Play framework.
The
secureDeleteFile
function first checks if the file exists. If it does, it creates a
RandomAccessFile
object for the file with "rws" mode, which allows reading and writing to the file.
A
SecureRandom
object is then created. This object generates cryptographically strong random numbers.
An array of bytes is created to store the random data. The file content is overwritten 10 times with this random data to ensure that the original data cannot be recovered.
After overwriting the file content, the
RandomAccessFile
is closed to release the resources associated with it.
Finally, the file is deleted using the
delete
method of the
File
class. This method deletes the file immediately, and it does not send the file to the Recycle Bin.
This approach ensures that the file is permanently deleted and that the original content of the file cannot be recovered, thus fixing the vulnerability.