Researchers at Trend Micro have uncovered a security hole that can be exploited to launch phishing attacks against users who make payments from their Android mobile devices.
According to the security firm, the vulnerability affects the in-app payment (IAP) SDKs for Google Wallet and Alibaba’s Alipay, China’s leading third-party online payment solution.
The flaw identified by researchers is related to what’s known as an “intent,” the software mechanism in Android that allows users to coordinate the functions of different apps to achieve a certain task.
“Explicit intents are used if the developer wants an action to be performed by a specific component in a specific app. Implicit intents are used when a developer allows the process to be performed by components of other apps,” Trend Micro Mobile Threats Analyst Weichao Sun explained in a blog post. “The Android platform uses intent-filters of apps to determine which app can perform the implicit intent. If an app contains the matching intent-filter, it can perform the task requested by the intent.”
The problem with Google Wallet and Alipay is that they use an implicit intent, and it can be intercepted with the aid of a “high priority” intent filter, which is made by combining multiple system APIs.
In the case of applications using Google Wallet, they communicate with Google Play, which informs the user about the payment and asks him/her to confirm the transaction. However, because the IAP SDK uses an implicit intent, a malicious application can use an intent filter that’s similar to the one that’s normally utilized to intercept the intent and display a phishing page instead of the regular window.
“Third party apps employ Google Wallet or Alipay SDK to communicate to the legitimate Google Wallet or Alipay SDK and for real payment process. The purpose of the said SDK is to send the pay intent to the Google Wallet or Alipay. A malicious app can replace the real Google Wallet or Alipay to receive the payment intent,” Sun explained.
Cybercriminals can leverage such techniques to trick users into handing over their account credentials. With this piece of information in hand, they can access the accounts in an effort to obtain other personal and financial details. The stolen information can be monetized directly or sold on the underground market, experts said.
Trend Micro reported the vulnerability to Alipay and Google on May 27. Alipay addressed the issue in mid-July with the release of version 2.0 of the SDK. Google says the latest version of its SDK offers better security and is encouraging developers to use it. The search engine giant also noted that it hasn’t seen any evidence to suggest that the vulnerability is being exploited in the wild.
“Developers should always use explicit intents for processes dealing with sensitive information. In such cases, only the desired app will be able to perform the process, minimizing the possibility of interception via malicious app. However, explicit intents are not enough,” the mobile threat analyst said. “Developers can also require that their apps check for the signatures of other apps as proof of their legitimacy before communicating with them.”
