How to Virus Scan File Uploads and Detect Insecure Deserialization Threats in Java

If our file upload process deserializes malicious data provided by a client-side threat actor, our system can become quickly compromised. Validating and sanitizing inputs is key to avoiding insecure deserialization attempts (which are most often carried out through JSON files in JID attacks).

The API provided in this article allows you to detect and block insecure deserialization attempts hidden within content uploads, while simultaneously scanning that content for viruses and malware (referencing a list of more than 17 million virus and malware signatures, including ransomware, spyware, trojans, and more). This solution can help make any file upload process more secure and protect your system — and your client-side users’ systems — from becoming compromised.

Below, you can use ready-to-run Java code examples to structure your API call and authenticate your request with a free-tier API key (you can get one from the Cloudmersive website).

Start by adding a reference to the repository in pom.xml. This begins client SDK installation with Maven:

<repositories>
    <repository>
        <id>jitpack.io</id>
        <url>https://jitpack.io</url>
    </repository>
</repositories>

Then add a reference to the pom.xml dependency:

<dependencies>
<dependency>
    <groupId>com.github.Cloudmersive</groupId>
    <artifactId>Cloudmersive.APIClient.Java</artifactId>
    <version>v4.25</version>
</dependency>
</dependencies>

Now you can copy the below Java examples to structure your API call. Supply your API key and set allowInsecureDeserialization to “false” to block any detected insecure deserialization attempts:

// Import classes:
//import com.cloudmersive.client.invoker.ApiClient;
//import com.cloudmersive.client.invoker.ApiException;
//import com.cloudmersive.client.invoker.Configuration;
//import com.cloudmersive.client.invoker.auth.*;
//import com.cloudmersive.client.ScanApi;

ApiClient defaultClient = Configuration.getDefaultApiClient();

// Configure API key authorization: Apikey
ApiKeyAuth Apikey = (ApiKeyAuth) defaultClient.getAuthentication("Apikey");
Apikey.setApiKey("YOUR API KEY");
// Uncomment the following line to set a prefix for the API key, e.g. "Token" (defaults to null)
//Apikey.setApiKeyPrefix("Token");

ScanApi apiInstance = new ScanApi();
File inputFile = new File("/path/to/inputfile"); // File | Input file to perform the operation on.
Boolean allowExecutables = true; // Boolean | Set to false to block executable files (program code) from being allowed in the input file.  Default is false (recommended).
Boolean allowInvalidFiles = true; // Boolean | Set to false to block invalid files, such as a PDF file that is not really a valid PDF file, or a Word Document that is not a valid Word Document.  Default is false (recommended).
Boolean allowScripts = true; // Boolean | Set to false to block script files, such as a PHP files, Python scripts, and other malicious content or security threats that can be embedded in the file.  Set to true to allow these file types.  Default is false (recommended).
Boolean allowPasswordProtectedFiles = true; // Boolean | Set to false to block password protected and encrypted files, such as encrypted zip and rar files, and other files that seek to circumvent scanning through passwords.  Set to true to allow these file types.  Default is false (recommended).
Boolean allowMacros = true; // Boolean | Set to false to block macros and other threats embedded in document files, such as Word, Excel and PowerPoint embedded Macros, and other files that contain embedded content threats.  Set to true to allow these file types.  Default is false (recommended).
Boolean allowXmlExternalEntities = true; // Boolean | Set to false to block XML External Entities and other threats embedded in XML files, and other files that contain embedded content threats.  Set to true to allow these file types.  Default is false (recommended).
Boolean allowInsecureDeserialization = true; // Boolean | Set to false to block Insecure Deserialization and other threats embedded in JSON and other object serialization files, and other files that contain embedded content threats.  Set to true to allow these file types.  Default is false (recommended).
Boolean allowHtml = true; // Boolean | Set to false to block HTML input in the top level file; HTML can contain XSS, scripts, local file accesses and other threats.  Set to true to allow these file types.  Default is false (recommended) [for API keys created prior to the release of this feature default is true for backward compatability].
String restrictFileTypes = "restrictFileTypes_example"; // String | Specify a restricted set of file formats to allow as clean as a comma-separated list of file formats, such as .pdf,.docx,.png would allow only PDF, PNG and Word document files.  All files must pass content verification against this list of file formats, if they do not, then the result will be returned as CleanResult=false.  Set restrictFileTypes parameter to null or empty string to disable; default is disabled.
try {
    VirusScanAdvancedResult result = apiInstance.scanFileAdvanced(inputFile, allowExecutables, allowInvalidFiles, allowScripts, allowPasswordProtectedFiles, allowMacros, allowXmlExternalEntities, allowInsecureDeserialization, allowHtml, restrictFileTypes);
    System.out.println(result);
} catch (ApiException e) {
    System.err.println("Exception when calling ScanApi#scanFileAdvanced");
    e.printStackTrace();
}

With these policies in place, any uploads containing viruses and malware — as well as insecure deserialization attempts — will receive a CleanResult: False Boolean in the API response body, allowing you to easily delete or quarantine potential threats.