What Is Phone Spear Phishing and How to Avoid Such Attack

Twitter recently shed a light on the cyberattack that compromised the accounts of a number of its high-profile customer base.

In the blog post “An update on our security incident”, Twitter said that the cyber incident that happened on July 15, 2020 targeted a small number of employees through a “phone spear phishing attack”. Twitter didn’t give details about how the attackers carried out the phone spear phishing attack.

Twitter, however, described the aftermath of the phone spear phishing attack. The company said that while not all of the Twitter employees that were targeted by the phone spear phishing attack had permissions to use Twitter’s account management tools, the “attackers” used the credentials gathered from the phone spear phishing attack to access the company’s internal systems and gain information about its processes.

Knowledge of the company’s internal systems and processes, Twitter said, enabled the attackers to target additional employees who did have access to the platform’s account support tools. Armed with credentials from employees that had access to the platform’s account support tools, Twitter said, the attackers targeted 130 Twitter accounts. Out of the 130 Twitter accounts, the company said, the attackers tweeted from 45 accounts, accessed the Direct Message (DM) inbox of 36 accounts, and downloaded the Twitter data of 7 accounts.

The phone spear phishing attack on Twitter compromised multiple high-profile verified accounts of personalities, including that of Bill Gates, Elon Musk and Jeff Bezos. Verified accounts of tech giants such as Apple and Uber as well as verified accounts of cryptocurrency exchanges such as Binance and Coinbase were also compromised.

Compromised verified accounts were made part of a cryptocurrency scam in which readers were called on to send bitcoin to a particular address with the promise that twice the amount of bitcoin would be returned. As of August 3, 2020, a total of 399 transferees sent bitcoin to the address mentioned in the compromised Twitter accounts. The total amount sent reached nearly 12.87 bitcoin (equivalent to USD 144,213).

As of July 30, 2020 (date of a case filed by the U.S. Department of Justice against one of the alleged perpetrators of the Twitter hack), not one of those that sent bitcoin to the above-mentioned address got their bitcoin doubled nor their bitcoin returned. Last July 31st, the U.S. Department of Justice announced that 3 cases had been filed against 3 individuals for their alleged roles in the Twitter hack.

Details of the alleged phone spear phishing attack are still not available despite the cases filed as the alleged mastermind of the Twitter hack is a minor. In the U.S., cases against minors aren’t available to the public.

Vishing

Phone spear phishing attack isn’t something new. Phishing attack, in general, refers to a cyberattack that tricks victims into giving information to criminals. Spear phishing, meanwhile, refers to a phishing campaign that targets specific individuals or specific organizations.

Traditionally, spear phishing attacks are conducted via emails. With the adoption of the Voice over Internet Protocol (VoIP) – a technology that allows users to make voice calls over the internet instead of a regular (or analog) phone line, phone phishing, also known as vishing, proliferate.

It’s rare to hear about phone phishing because such are reported under the category of phishing which includes traditional email phishing. In a typical email phishing, an attacker sends a target an email that masquerades as coming from a legitimate source.

This malicious email contains a malicious link or attachment. Clicking on this malicious link or attachment could lead to the compromise of the user’s computer or stealing of sensitive data.

In the early 2000s, the Federal Bureau of Investigation (FBI) cited two examples of vishing. In one version of a vishing scam, a target receives a typical email, similar to the traditional email phishing scam. But instead of directing the target to a malicious link, the target is given a phone number (a VoIP account) to call and ask to provide certain information over the given phone number.

The phone number is usually that of a fake customer service. The target that calls the customer service is then directed to a series of voice-prompted menus that ask for passwords and other sensitive information.

According to the FBI, another version of vishing directly contacts the target by phone (VoIP account as well) instead of an initial email. The call can come from a recorded message directing the target to take action to protect his or her account. In this case, the attacker already has some personal information about the target. This gives the target a false sense of security.

Vishing via VoIP, the FBI said, has some advantages over traditional phishing tricks due to the following reasons:

• VoIP service is relatively inexpensive, making it cheap to make fake long-distance calls.
• VoIP is web-based and criminals can use malicious software to create phony automated customer service lines. Threat actors can mask the malicious VoIP number as coming from a legitimate VoIP number. In some cases, the VoIP number belongs to a legitimate subscriber whose service has been hacked.

Preventive and Mitigating Measures Against Vishing

Always treat a phone call asking for sensitive information with a healthy dose of skepticism. Verify whether the call is legitimate by hanging up the phone and calling the customer service using the number provided by the organization.