Category Archives: IMAP

E Hacking News – Latest Hacker News and IT Security News: Multi-factor authentication bypassed to hack Office 365 & G Suite Cloud accounts



Massive IMAP-based password-spraying attacks successfully breached Microsoft Office 365 and G Suite accounts, circumventing multi-factor authentication (MFA) according to an analysis by Proofpoint.

As noted by Proofpoint's Information Protection Research Team in a recent report, during a "recent six-month study of major cloud service tenants, Proofpoint researchers observed attackers are targeting legacy protocols with stolen credential dumps to increase the speed and efficiency of the brute force attacks.

Based on Proofpoint study, IMAP is the most abused protocol, IMAP is the protocol that bypasses MFA and lock-out options for failed logins.

This technique takes advantage of the fact that the legacy authentication IMAP protocol bypasses MFA, allowing malicious actors to perform credential stuffing attacks against assets that would have been otherwise protected.

These intelligent new brute force attacks bring a new approach to the traditional normal brute force attack that uses the combination of usernames and passwords.

Based on the Proofpoint analysis of over one hundred thousand unauthorized logins across millions of monitored cloud user-accounts and found that:

▬ 72% of tenants were targeted at least once by threat actors
▬ 40% of tenants had at least one compromised account in their environment
▬ Over 2% of active user-accounts were targeted by malicious actors
▬ 15 out of every 10,000 active user-accounts were successfully breached by attackers

Their analysis unearthed the fact that around 60% of all Microsoft Office 365 and G Suite tenants have been targeted using IMAP-based password-spraying attacks and, as a direct result, approximately 25% of G Suite and Office 365 tenants that were attacked also experienced a successful breach.

On the whole, after crunching down the numbers, Proofpoint reached the conclusion that threat actors managed to reach a surprising 44% success rate when it came to breaching accounts at targeted organizations.

The ultimate aim of the attackers is to launch internal phishing and to have a strong foothold within the organization. Internal phishing attempts are hard to detect when compared to the external ones.


E Hacking News - Latest Hacker News and IT Security News

Multi-factor authentication bypassed to hack Office 365 & G Suite Cloud accounts



Massive IMAP-based password-spraying attacks successfully breached Microsoft Office 365 and G Suite accounts, circumventing multi-factor authentication (MFA) according to an analysis by Proofpoint.

As noted by Proofpoint's Information Protection Research Team in a recent report, during a "recent six-month study of major cloud service tenants, Proofpoint researchers observed attackers are targeting legacy protocols with stolen credential dumps to increase the speed and efficiency of the brute force attacks.

Based on Proofpoint study, IMAP is the most abused protocol, IMAP is the protocol that bypasses MFA and lock-out options for failed logins.

This technique takes advantage of the fact that the legacy authentication IMAP protocol bypasses MFA, allowing malicious actors to perform credential stuffing attacks against assets that would have been otherwise protected.

These intelligent new brute force attacks bring a new approach to the traditional normal brute force attack that uses the combination of usernames and passwords.

Based on the Proofpoint analysis of over one hundred thousand unauthorized logins across millions of monitored cloud user-accounts and found that:

▬ 72% of tenants were targeted at least once by threat actors
▬ 40% of tenants had at least one compromised account in their environment
▬ Over 2% of active user-accounts were targeted by malicious actors
▬ 15 out of every 10,000 active user-accounts were successfully breached by attackers

Their analysis unearthed the fact that around 60% of all Microsoft Office 365 and G Suite tenants have been targeted using IMAP-based password-spraying attacks and, as a direct result, approximately 25% of G Suite and Office 365 tenants that were attacked also experienced a successful breach.

On the whole, after crunching down the numbers, Proofpoint reached the conclusion that threat actors managed to reach a surprising 44% success rate when it came to breaching accounts at targeted organizations.

The ultimate aim of the attackers is to launch internal phishing and to have a strong foothold within the organization. Internal phishing attempts are hard to detect when compared to the external ones.

Massive attacks bypass MFA on Office 365 and G Suite accounts via IMAP Protocol

Threat actors targeted Office 365 and G Suite cloud accounts using the IMAP protocol to bypass multi-factor authentication (MFA).

Over the past months, threat actors have targeted Office 365 and G Suite cloud accounts using the IMAP protocol to bypass multi-factor authentication (MFA).

Experts at Proofpoint conducted an interesting study of massive attacks against accounts of major cloud services, The experts noticed that attackers leverage legacy protocols and credential dumps to increase the efficiency of massive brute force attacks.

Attacks against Office 365 and G Suite cloud accounts using IMAP are difficult to protect against with multi-factor authentication, where service accounts and shared mailboxes are notably vulnerable.” reads the study published by Proofpoint. “At the same time, targeted, intelligent brute force attacks brought a new approach to traditional password-spraying, employing common variations of the usernames and passwords exposed in large credential dumps to compromise accounts.”

The experts analyzed over one hundred thousand unauthorized logins across millions of monitored cloud user-accounts, below key findings from the study:

  • 72% of tenants were targeted at least once by threat actors  
  • 40% of tenants had at least one compromised account in their environment  
  • Over 2% of active user-accounts were targeted by malicious actors 
  • 15 out of every 10,000 active user-accounts were successfully breached by attackers 

The attacker’s primary goal is to carry out internal phishing, especially when the initial target does not have the access needed to transfer money or data. The access to a cloud account could be exploited by attackers for lateral movements and to expand footholds within an organization via internal phishing and internal BEC. Experts observed that compromised accounts are also used to launch external attacks.    

Giving a look at the sources of the attacks, most of them come from Nigerian IP addresses (40%), followed by Chinese IP addresses (26%).

According to the study, IMAP was the most abused legacy protocol. IMAP is a legacy authentication protocol that bypasses multifactor authentication (MFA). Experts pointed out that these attacks avoid account lock-out and appear as isolated failed logins and for this reason, they are hard to detect.

Below other data provided by the experts:

  • Approximately 60% of Microsoft Office 365 and G Suite tenants were targeted with IMAP-based password-spraying attacks 
  • Roughly 25% of Office 365 and G Suite tenants experienced a successful breach as a result 
  • Threat actors achieved a 44% success rate breaching an account at a targeted organization 

The experts observed a large number of IMAP-based password-spraying campaigns between September 2018 and February 2019. Proofpoint reported that 10% of active user accounts in targeted tenants were hit and 1% of targeted user accounts were successfully breached.

IMAP protocol attacks phishing

The attackers leveraged a botnet composed of thousands of hijacked network devices (i.e. routers, servers) to launch the attacks.

“These hijacked devices gained access to a new tenant every 2.5 days on average during a 50-day period,” continues Proofpoint.

China was the source for the vast majority of the IMAP-based attacks (53%), followed by Brazil (39%) and the United States (31%).

Most of the attacks (63%) originated from Nigerian IP addresses, followed by South African infrastructure (21%), and the United States via VPNs (11%).

This study demonstrates the increasing sophistication of threat actors around the world who are leveraging brute force methods, massive credential dumps, and successful phishing attacks to compromise cloud accounts at unprecedented scale. Service accounts and shared mailboxes are particularly vulnerable while multifactor authentication has proven vulnerable.” concludes the study.

“Attackers parlay successful compromises into internal phishing attacks, lateral movement in organizations, and additional compromises at trusted external organizations.”

Pierluigi Paganini

(SecurityAffairs – IMAP, hacking)

The post Massive attacks bypass MFA on Office 365 and G Suite accounts via IMAP Protocol appeared first on Security Affairs.

Security Affairs: Massive attacks bypass MFA on Office 365 and G Suite accounts via IMAP Protocol

Threat actors targeted Office 365 and G Suite cloud accounts using the IMAP protocol to bypass multi-factor authentication (MFA).

Over the past months, threat actors have targeted Office 365 and G Suite cloud accounts using the IMAP protocol to bypass multi-factor authentication (MFA).

Experts at Proofpoint conducted an interesting study of massive attacks against accounts of major cloud services, The experts noticed that attackers leverage legacy protocols and credential dumps to increase the efficiency of massive brute force attacks.

Attacks against Office 365 and G Suite cloud accounts using IMAP are difficult to protect against with multi-factor authentication, where service accounts and shared mailboxes are notably vulnerable.” reads the study published by Proofpoint. “At the same time, targeted, intelligent brute force attacks brought a new approach to traditional password-spraying, employing common variations of the usernames and passwords exposed in large credential dumps to compromise accounts.”

The experts analyzed over one hundred thousand unauthorized logins across millions of monitored cloud user-accounts, below key findings from the study:

  • 72% of tenants were targeted at least once by threat actors  
  • 40% of tenants had at least one compromised account in their environment  
  • Over 2% of active user-accounts were targeted by malicious actors 
  • 15 out of every 10,000 active user-accounts were successfully breached by attackers 

The attacker’s primary goal is to carry out internal phishing, especially when the initial target does not have the access needed to transfer money or data. The access to a cloud account could be exploited by attackers for lateral movements and to expand footholds within an organization via internal phishing and internal BEC. Experts observed that compromised accounts are also used to launch external attacks.    

Giving a look at the sources of the attacks, most of them come from Nigerian IP addresses (40%), followed by Chinese IP addresses (26%).

According to the study, IMAP was the most abused legacy protocol. IMAP is a legacy authentication protocol that bypasses multifactor authentication (MFA). Experts pointed out that these attacks avoid account lock-out and appear as isolated failed logins and for this reason, they are hard to detect.

Below other data provided by the experts:

  • Approximately 60% of Microsoft Office 365 and G Suite tenants were targeted with IMAP-based password-spraying attacks 
  • Roughly 25% of Office 365 and G Suite tenants experienced a successful breach as a result 
  • Threat actors achieved a 44% success rate breaching an account at a targeted organization 

The experts observed a large number of IMAP-based password-spraying campaigns between September 2018 and February 2019. Proofpoint reported that 10% of active user accounts in targeted tenants were hit and 1% of targeted user accounts were successfully breached.

IMAP protocol attacks phishing

The attackers leveraged a botnet composed of thousands of hijacked network devices (i.e. routers, servers) to launch the attacks.

“These hijacked devices gained access to a new tenant every 2.5 days on average during a 50-day period,” continues Proofpoint.

China was the source for the vast majority of the IMAP-based attacks (53%), followed by Brazil (39%) and the United States (31%).

Most of the attacks (63%) originated from Nigerian IP addresses, followed by South African infrastructure (21%), and the United States via VPNs (11%).

This study demonstrates the increasing sophistication of threat actors around the world who are leveraging brute force methods, massive credential dumps, and successful phishing attacks to compromise cloud accounts at unprecedented scale. Service accounts and shared mailboxes are particularly vulnerable while multifactor authentication has proven vulnerable.” concludes the study.

“Attackers parlay successful compromises into internal phishing attacks, lateral movement in organizations, and additional compromises at trusted external organizations.”

Pierluigi Paganini

(SecurityAffairs – IMAP, hacking)

The post Massive attacks bypass MFA on Office 365 and G Suite accounts via IMAP Protocol appeared first on Security Affairs.



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