The Threat:

A recent Office365 phishing campaign has shown that threat actors are switching tactics to include the use of Google infrastructure. On October 16th, 2019, both eSentire and external sources observed the use of Google storage to host phishing pages [1]. The use of Google infrastructure has been implemented by threat actors in an attempt to bypass standard email protection. Employees and administrators are encouraged to review the phishing examples and recommendations below.

What we’re doing about it:

  • Identified phishing pages have been reported to Google
  • Credential dump pages are being monitored and added to the eSentire Global Blacklist as they become available
  • The eSentire Threat Intelligence Team is actively monitoring this threat for additional information

What you should do about it:

All Employees

  • Review below images of recent phishing emails for examples of what to expect
  • Review emails for suspicious indicators (such as unknown sender/ suspicious URLs) prior to opening links or attachments
  • Be cautious of generic Office 365 login pages lacking branding for your organization

Network/Email Administrators

  • Enforce the use of Multi-Factor Authentication for corporate email accounts
  • Consult your email security provider to ensure phishing emails using “storage.googleapis[.]com” links are sufficiently blocked
  • Implement Exchange rules to redirect emails containing “storage.googleapis[.]com” to a monitored inbox
    • This prevention method has a medium-high chance of false positives

Additional information:

Multiple phishing pages have been identified using storage.googleapis[.]com to host Office 365 credential phishing pages (Figure 1). These attacks are similar to previous phishing campaigns which exploited blob[.]core[.]windows[.]net and azurewebsites[.]net to host phishing pages. Preliminary investigations show that multiple phishing campaigns are employing a similar prefabricated phishing kit (Figure 3).

The October 16th, 2019 observed attacks were delivered through low effort phishing emails (Figure 2). If a user inserts credentials into the phishing page, the credentials are then sent to a credential drop site for storage (Figures 4 & 5).

Multi-factor authentication (MFA) phishing attempts were not identified in this campaign. It should be noted that attacks specifically targeting MFA have been identified in the wild [2]. Despite these instances, employing MFA is still considered a best security practice for prevent account compromise.

For more information on past phishing campaigns, see the eSentire advisories Office 365 Phishing Follow-Up and Hex Encoded Links Point to Phishing Pages on Microsoft Cloud Services [3] [4].

Figure 1: Office 365 credential phishing pagefig1 v2

Figure 2: Phishing Email leading to storage[.]googleapis[.]com credential phishing page
fig2 v3
Figure 3: Phishing kit HTML
fig3 v2

Figure 4: Credential Drop Site
fig4 v2 

Figure 5: Example of plain text phished credentials
fig5 v2

 

Indicator Type

Indicators of Compromise

Description

URL

https://storage[.]googleapis[.]com/aoffice365-perpession-70360561/index[.]html

Credential Phishing Page

URL

https://storage.googleapis[.]com/inboxvoicenotemsg/realm/recover[.]html

Credential Phishing Page

URL

https://sendapidata[.]com/email-list/finish-unv2[.]php

Credential Drop Site

URL

https://bertelgrenda[.]top/msgoff/azure2019/realm/send[.]php

Credential Drop Site

URL

https://reklas[.]ga/[email protected]/azure2019/

Credential Drop Site

Email Address

[email protected][.]co[.]jp

Sender Address

 

References:

[1] https://twitter.com/KesaGataMe0/status/1184354076131151872

[2] https://info.publicintelligence.net/FBI-CircumventingMultiFactorAuthentication.pdf

[3] https://www.esentire.com/security-advisories/office-365-phishing-follow-up/

[4] https://www.esentire.com/security-advisories/hex-encoded-links-point-to-phishing-pages-on-microsoft-cloud-services/

 

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Articles and reports written by eSentire staff and our Threat Intelligence Research Group.

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