Dark Reading is part of the Informa Tech Division of Informa PLC

This site is operated by a business or businesses owned by Informa PLC and all copyright resides with them.Informa PLC's registered office is 5 Howick Place, London SW1P 1WG. Registered in England and Wales. Number 8860726.

Endpoint

8/30/2017
02:20 PM
Connect Directly
Twitter
LinkedIn
RSS
E-Mail
0%
100%

Office 365: A Vehicle for Internal Phishing Attacks

A new threat uses internal accounts to spread phishing attacks, making fraudulent emails even harder to detect.

Cybercriminals go where the users are. Office 365, which has more than 100 million active monthly subscribers, has become a hotspot for compelling and personalized cyberattacks. Users trust emails from coworkers, especially those with the correct corporate email address.

Traditional phishing attempts have red flags: suspicious attachments, bold requests, misspelled words, questionable email addresses. Users know how to react to these. But what happens when attacks are more personalized, with legitimate addresses and reasonable requests?

These have become more popular and tougher to spot, says Asaf Cidon, spearphishing expert at Barracuda. The company recently released a report on a threat he calls Account Compromise. Once they have an employee's Office 365 account information, threat actors can craft realistic-looking messages and send them from an account their victims trust.

Attackers primarily steal credentials using traditional methods, he continues. Most rely on phishing or spearphishing to send victims to fraudulent websites, where they are prompted to reset their Office 365 credentials. Some buy users' credentials on the dark web.

"What's new is what happens after they get access to the accounts," Cidon says. Threat actors can conduct several types of attacks after they gain a foothold in an organization.

In one common scenario, an attacker sets forwarding rules on an Office 365 account to send emails to an account they control. From there, they can both steal data and monitor the user's internal and external communication patterns so they can plan future attacks.

Threat actors also impersonate their victims and send emails to other employees with the goal of collecting data. Some send emails with PDF attachments that can only be opened with a username and password. Some send an invoice for payment that requires logging into a web portal, where they have to log in with a corporate email address and password.

Damage could potentially extend outside the organization. Cidon explains a scenario in which an attacker, impersonating an employee, used their access to request a wire transfer from a partner company. The employee in the scenario didn't even realize the transfer was happening.

"This is an evolution of spearphishing - we're seeing more and more sophistication," he says. A couple of years ago, cyberattackers primarily targeted executive employees. These new Office 365 threats are putting all employees at risk.

"With this attack, they're just trying to get in and once they're in, a lot of the employees getting targeted are not high-level. It's not just executive targets," Cidon continues.

There are red flags that signify a company is targeted in one of these attacks. Oftentimes the IP addresses used to log into corporate accounts come from other countries, he says, and looking at the log can identify geographical anomalies. It also helps to keep track of your email account to see when emails are getting forwarded or sent to unfamiliar addresses.

Cidon advises security leaders to train employees on how to spot phishing attacks to prevent attackers gaining initial access. He also advises adding security layers like multi-factor authentication to Office 365 to lessen the chance of a break-in.

"Traditional email security systems are going to be almost useless in stopping this," he says, noting how most tools look at the API of the email provider. "Once an attacker is in, they don't see internal emails … only the external emails coming in."

Related Content:

Learn from the industry’s most knowledgeable CISOs and IT security experts in a setting that is conducive to interaction and conversation. Click for more info and to register.

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
 

Recommended Reading:

Comment  | 
Print  | 
More Insights
Comments
Newest First  |  Oldest First  |  Threaded View
EKFletcher
50%
50%
EKFletcher,
User Rank: Apprentice
9/4/2017 | 11:47:37 AM
IP addresses outside the US
Nice information.  Thank you. 

How can someone with a list of IP addresses showing where the users have signed in from take that and easily tell what IPs are from another contry?  If you have hundreds of IPs, it would be a daunting task to discover if any IPs were from another contry.

Thanks! 
News
Inside the Ransomware Campaigns Targeting Exchange Servers
Kelly Sheridan, Staff Editor, Dark Reading,  4/2/2021
Commentary
Beyond MITRE ATT&CK: The Case for a New Cyber Kill Chain
Rik Turner, Principal Analyst, Infrastructure Solutions, Omdia,  3/30/2021
Register for Dark Reading Newsletters
White Papers
Video
Cartoon
Current Issue
2021 Top Enterprise IT Trends
We've identified the key trends that are poised to impact the IT landscape in 2021. Find out why they're important and how they will affect you today!
Flash Poll
How Enterprises are Developing Secure Applications
How Enterprises are Developing Secure Applications
Recent breaches of third-party apps are driving many organizations to think harder about the security of their off-the-shelf software as they continue to move left in secure software development practices.
Twitter Feed
Dark Reading - Bug Report
Bug Report
Enterprise Vulnerabilities
From DHS/US-CERT's National Vulnerability Database
CVE-2021-30481
PUBLISHED: 2021-04-10
Valve Steam through 2021-04-10, when a Source engine game is installed, allows remote authenticated users to execute arbitrary code because of a buffer overflow that occurs for a Steam invite after one click.
CVE-2021-20020
PUBLISHED: 2021-04-10
A command execution vulnerability in SonicWall GMS 9.3 allows a remote unauthenticated attacker to locally escalate privilege to root.
CVE-2021-30480
PUBLISHED: 2021-04-09
Zoom Chat through 2021-04-09 on Windows and macOS allows certain remote authenticated attackers to execute arbitrary code without user interaction. An attacker must be within the same organization, or an external party who has been accepted as a contact. NOTE: this is specific to the Zoom Chat softw...
CVE-2021-21194
PUBLISHED: 2021-04-09
Use after free in screen sharing in Google Chrome prior to 89.0.4389.114 allowed a remote attacker to potentially exploit heap corruption via a crafted HTML page.
CVE-2021-21195
PUBLISHED: 2021-04-09
Use after free in V8 in Google Chrome prior to 89.0.4389.114 allowed a remote attacker to potentially exploit heap corruption via a crafted HTML page.