Threat Intelligence

2/27/2019
12:00 PM
Connect Directly
Twitter
LinkedIn
Google+
RSS
E-Mail
50%
50%

Whose Line Is It? When Voice Phishing Attacks Get Sneaky

Researchers investigate malicious apps designed to intercept calls to legitimate numbers, making voice phishing attacks harder to detect.

What if social engineers, instead of calling victims with voice phishing attacks, intercepted phone calls their victims make to legitimate phone numbers? Malicious apps let cybercriminals do just that – a tactic that puts a subtle twist on traditional voice phishing.

Min-Chang Jang, manager at Korea Financial Security Institute and Korea University, began investigating these apps in September 2017 when he received a report of an app impersonating a financial firm. Analysis revealed a phone interception feature in the app, which intrigued him.

That's how Jang discovered a new type of voice phishing crime, which combines traditional voice phishing with malicious apps to trick unsuspecting callers into chatting with cybercriminals.

Here's how they work: An attacker must first convince a victim to download an app. The attacker may send a link to the victim, enticing the person with something like a low-interest loan, and prompt him to install the app for it. If the target takes the bait and later calls a financial company for loan consultation, the call is intercepted and connected to the attacker.

"The victims believe that they are talking to a financial company employee, but they aren't," Jang says. It's unlikely victims will know a scam is taking place, he says. Most of these attacks mimic apps from financial firms.

Unfortunately, when Jang and his research team first discovered malicious apps with the interception feature, they didn't have access to a live malicious app distribution server because it had already been closed by the time they received victim reports. In April 2018, Jang found a live distribution server – a pivotal point for their research into malicious phishing apps.

This particular distribution server had a very short operating cycle, ranging from a few hours to two days. "I found it while monitoring community sites for the information gathering," Jang explains. He discovered a post written to educate users to be careful of phishing sites; fortunately, it discussed the malicious applications they were hoping to investigate.

"I found a specific string in the Web page source code of a live malware distribution server," he says, "and I used the string for scanning to get more malware distribution servers." 

With access to one server, researchers could check which of its ports were open and access the Web page source code. Based on those strings of code from the first distribution server, they were able to create a real-time malicious app collection script, Jang explains. The automated system they created is able to collect malware distribution servers and apps in near real time.

Using this script, researchers have been able to find malicious app distribution servers and variant malicious apps. Following their discovery of the first live distribution server, they have collected about 3,000 malicious apps from various servers. The command-and-control (C2) server address was hard-coded inside malicious apps, Jang says, and could be easily extracted.

Their research continued to unfold. The team analyzed the C2 server, where they discovered a file containing the account data they needed to access it. This data helped the team gain the privileges of the Windows server admin of the distribution server and of the database admin of the C2 server. A Remote Desktop Protocol (RDP) connection to the server led to more information – the team confirmed this attacker was connecting to the Internet via the Point-to-Point Protocol over Ethernet (PPPoE), a sign the server's location was in Taiwan.

In a presentation at Black Hat Asia, entitled "When Voice Phishing Met Malicious Android App," Jang will disclose and discuss the findings of criminal traces in voice phishing analysis conducted by his research team over the past few months.

 

 

Join Dark Reading LIVE for two cybersecurity summits at Interop 2019. Learn from the industry's most knowledgeable IT security experts. Check out the Interop agenda here.

Kelly Sheridan is the Staff Editor at Dark Reading, where she focuses on cybersecurity news and analysis. She is a business technology journalist who previously reported for InformationWeek, where she covered Microsoft, and Insurance & Technology, where she covered financial ... View Full Bio

Comment  | 
Print  | 
More Insights
Comments
Newest First  |  Oldest First  |  Threaded View
Joe Stanganelli
50%
50%
Joe Stanganelli,
User Rank: Ninja
2/28/2019 | 6:22:38 PM
Re: More app trouble
Yeah, I'm at the point where I just never answer the phone unless I either recognize the number or I'm specifically expecting a call. If it's a real person with a good reason for calling, they'll leave a voicemail.
REISEN1955
50%
50%
REISEN1955,
User Rank: Ninja
2/27/2019 | 3:52:03 PM
Re: More app trouble
Agree - NEVER trust the phone - we get scam calls all of the time and a few i enjoy such as telling the famous Microsoft engineer I have a bug on my system.  Takes anger to good use.  (My former manager is better, he tries then to upload ransomware to THEIR system for the revenge of it).   About 5% of inicoming calls are real and the rest junk.  Silence phone calls to - and spoof phone numbers.  Don't answer really unless sometimes I just want a bit of threathunting to see who calls.  
Joe Stanganelli
50%
50%
Joe Stanganelli,
User Rank: Ninja
2/27/2019 | 2:15:22 PM
More app trouble
Apps, extensions, add-ons, widgets -- just stay away from 'em, people, unless they are very well vetted.
Crowdsourced vs. Traditional Pen Testing
Alex Haynes, Chief Information Security Officer, CDL,  3/19/2019
BEC Scammer Pleads Guilty
Dark Reading Staff 3/20/2019
Register for Dark Reading Newsletters
White Papers
Video
Cartoon Contest
Write a Caption, Win a Starbucks Card! Click Here
Latest Comment: Well, at least it isn't Mobby Dick!
Current Issue
5 Emerging Cyber Threats to Watch for in 2019
Online attackers are constantly developing new, innovative ways to break into the enterprise. This Dark Reading Tech Digest gives an in-depth look at five emerging attack trends and exploits your security team should look out for, along with helpful recommendations on how you can prevent your organization from falling victim.
Flash Poll
The State of Cyber Security Incident Response
The State of Cyber Security Incident Response
Organizations are responding to new threats with new processes for detecting and mitigating them. Here's a look at how the discipline of incident response is evolving.
Twitter Feed
Dark Reading - Bug Report
Bug Report
Enterprise Vulnerabilities
From DHS/US-CERT's National Vulnerability Database
CVE-2019-9945
PUBLISHED: 2019-03-23
SoftNAS Cloud 4.2.0 and 4.2.1 allows remote command execution. The NGINX default configuration file has a check to verify the status of a user cookie. If not set, a user is redirected to the login page. An arbitrary value can be provided for this cookie to access the web interface without valid user...
CVE-2019-9942
PUBLISHED: 2019-03-23
A sandbox information disclosure exists in Twig before 1.38.0 and 2.x before 2.7.0 because, under some circumstances, it is possible to call the __toString() method on an object even if not allowed by the security policy in place.
CVE-2018-20165
PUBLISHED: 2019-03-22
Cross-site scripting (XSS) vulnerability in OpenText Portal 7.4.4 allows remote attackers to inject arbitrary web script or HTML via the vgnextoid parameter to a menuitem URI.
CVE-2019-1716
PUBLISHED: 2019-03-22
A vulnerability in the web-based management interface of Session Initiation Protocol (SIP) Software for Cisco IP Phone 7800 Series and Cisco IP Phone 8800 Series could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition or execute arbitrary code. The vulnerability ...
CVE-2019-1763
PUBLISHED: 2019-03-22
A vulnerability in the web-based management interface of Session Initiation Protocol (SIP) Software for Cisco IP Phone 8800 Series could allow an unauthenticated, remote attacker to bypass authorization, access critical services, and cause a denial of service (DoS) condition. The vulnerability exist...