OWASP category: MASVS-NETWORK: Network Communication
Allowing cleartext network communications in an Android app means that anyone monitoring network traffic can see and manipulate the data that is being transmitted. This is a vulnerability if the transmitted data includes sensitive information such as passwords, credit card numbers, or other personal information.
Regardless of if you are sending sensitive information or not, using cleartext can still be a vulnerability as cleartext / plaintext HTTP traffic can also be manipulated through network poisoning attacks such as ARP or DNS poisoning, thus potentially enabling attackers to influence the behavior of an app.
When an Android application sends or receives data in cleartext over a network, anyone who is monitoring the network can intercept and read that data. If this data includes sensitive information such as passwords, credit card numbers, or personal messages, this can lead to identity theft, financial fraud, and other serious problems.
For example, an app transmitting passwords in cleartext could expose these credentials to a malicious actor intercepting the traffic. This data could then be used to gain unauthorized access to the user's accounts.
The guidance in this section applies only to apps that target Android 8.1 (API level 27) or lower. Starting with Android 9 (API level 28), cleartext support is disabled by default.
Use the NetworkSecurityConfig.xml functionality to opt-out of cleartext traffic:
<?xml version="1.0" encoding="utf-8"?>
This option helps prevent accidental regressions in apps due to changes in URLs provided by external sources such as backend servers.