Security Experts:

API Vulnerability Exposed Accounts of Delmarva Power Customers

A malicious attacker could have hijacked the online accounts of Delmarva Power customers by leveraging a vulnerability in the company’s API, a researcher reported on Sunday.

Delmarva Power is a Pepco Holdings subsidiary that provides power services in Delaware and Maryland. According to its website, the company has 503,000 electric and 122,000 gas customers.

After analyzing the company’s Android application, which has been downloaded between 10,000 and 50,000 times from Google Play, software developer and security researcher Randy Westergren discovered that the API is plagued by Insecure Direct Object Reference (IDOR) vulnerabilities that can be exploited to take over customer accounts.

By performing a man-in-the-middle (MitM) attack against his own account, the expert discovered that the login request contained a user ID. An attacker could have accessed any account simply by changing the value of this user ID parameter, despite the fact that the request also contained a session cookie and an authentication key.

The researcher found that the response from the server contained a lot of personal information, including the user’s address, payment details, and security questions/answers.

“Using this information, an attacker could have easily reset any user’s password and gained complete control over their account,” Westergren explained in a blog post.

The expert also discovered that he could access any customer’s bill in PDF format simply by changing the value of the “accountNumber” parameter. Payment information could not be obtained through this method, but an attacker could have viewed partial payment data by resetting a customer’s password and accessing their account.

“It seems payment accounts on the app are independent of the Delmarva Power web application. Though I had a feeling this request was also vulnerable, I didn’t confirm it,” the researcher said.

The vulnerability was first reported to Delmarva Power in November. However, it took Westergren until January 8 to get in touch with the right person at the company and another two weeks until a patch was rolled out. The company sent the researcher a gift card for his effort.

“Our customer's online safety is always a priority. We take all security issues very seriously. Once we were informed of the issue our company took immediate action to resolve the situation and protect our customers,” Delmarva Power said in an emailed statement.

This isn’t the first time Westergren finds serious vulnerabilities in the mobile apps of high-profile organizations. In January, he reported finding a security hole that exposed the email accounts of Verizon customers, and a flaw that could have been exploited to gain access to the details of Marriott customers.

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Eduard Kovacs (@EduardKovacs) is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.