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By Ashley Tran, Cofense Phishing Defense Center

The Cofense Phishing Defense Center (PDC) has observed a new phishing campaign that aims to harvest a variety of email credentials specifically from United States citizens.

Countries all around the world are providing relief programs to their citizens to help alleviate the financial strain as a result of the COVID-19 pandemic. This threat actor, however, targets US relief efforts and the citizens who need it most. This email campaign uses the logo of the Internal Revenue Service (IRS) to bolster its credibility.

Figure 1: Email Preview

The threat actor made both the subject and sender information eye catching, as seen in Figure 1. The email appears to be from ‘IRS GOV’ regarding the subject “Tax Relief Fund,” which would be enough to gain the attention of anyone, especially those who may not have received their relief or need more. Upon clicking into the email, users are presented with the following message, as seen in Figure 2 below.

Figure 2-3: Email Body

Despite the image missing from this email sample, assumed to once have been a DocuSign logo based on the image description, the email may appear legitimate at first glance. The IRS has sent a secure document via DocuSign along with a security code to view it, but it must be used soon as it will “expire.” The email is also marked “High Importance.”

A closer look at the body of the email reveals many warning signs this email is a phish. Anyone acquainted with DocuSign would know this is not what an invitation from the service looks like. Not to mention there is odd spacing and capitalization found in the text – atypical for professional emails. There is also mention of a security code that must be used “before expiration,” a common social engineering tactic used to illicit a sense urgency.

The link found in the email, “View Shared Folder,” redirects users to the phishing site located at:

hxxp://playdemy[.]org/office/doc-new

Figures 4-5: Phishing Page and Confirmation Page

Figures 4-5 are examples of the first page users will see upon navigating through the link found in the email. The page is a simple DocuSign page prompting for the user’s email address in order to access the promised document. Visually there aren’t many differences compared to DocuSign’s website, other than the incorrect URL displayed in the address bar. However, the threat actor may have intentionally used a .org-based domain to make it appear safe, as many end users have heard .org top-level domains are “secure.”

Should a user proceed to enter their email address on this page, they are prompted once again to verify the information before being redirected to the next step of this attack.

Figures 6-7: AOL login page

The next step involves redirecting users to a phishing page based on their email provider. In Figures 6-7 above, we used a dummy AOL email and were redirected to an AOL phish. The attacker’s AOL login page rivals the look and feel of AOL’s — the only real difference is the incorrect URL in the address bar. The email entered in the first step is already pre-filled as well. This same occurs with other email providers inputted into the first step of the attack. Figures 8-10, for example, show the Gmail phish that users are redirected to if that was the email provider they entered.

Figures 8-10: Alternative Gmail Phish

Should a user enter an email address to proceed this far, the threat actor has made sure to ask for further compromising information, as seen in Figure 10: a recovery number or recovery email address per their back-up login information.

Figure 11: Final Destination

Regardless of the email address, and should the user enter this information, users are then redirected to an unexpected document; in lieu of the promised “Tax Relief Fund,” they see a completely unrelated academic paper hosted on Harvard Business School’s website. This is a common tactic, designed to confuse users into thinking there is nothing amiss, that perhaps this was a mistaken exchange or they received the wrong document in error and must wait for further contact.

Further analysis of the website utilized for this attack yielded further information on the attack and the actors behind it.

Figure 12: Open Directory

Upon navigating to the main domain, as shown in Figure 12, an open directory appears. While the file Chetos.php is password protected at present, the file 039434.php exposes a greater security threat that can be observed in Figure 13, a web shell.

Figure 13: WebAccess Shell

The beginnings of a malicious web shell start with an attacker methodically installing the malicious script for the shell on the targeted site, either by SQL injection or cross-site scripting. From there the web shell is utilized by attackers to maintain persistent access to a compromised website without having to repeat all the work of exploiting the same vulnerability they used the first time – generally, a backdoor. They can remotely execute commands and manage files that they abuse to carry out their attacks, such as a phishing attack.
As observed in Figure 13, investigation of the shell reveals files from the open directory are displayed, last modified 2020-04-24 by “owner/group” “njlugdc”, otherwise known as the attacker. The real guts of this attack, however, can be found within the directory path office/doc-new seen in Figure 14.

Figure 14: office/doc-new Directory

Within the directory are the many steps in what appears to be a simple phish. There are multiple email branded folders such as “a0l”, “earthl1nk”, “gma1l,” all of which help the threat actor target email clients. Each of these email branded folders host a phish that is specifically tailored to that brand, allowing for a more “authentic” experience that lull users into a sense of security.

Figure 15: Code Behind the Attack

Figure 15 demonstrates the code behind the attack that sanitizes user input to determine which of these phish a user is redirected to, along with the associated email brand logo to display during the redirect process.

Figure 16: Threat Actor Emails Exposed

Within the files contained in this web shell, the threat actor’s emails are displayed. Figure 16 shows the code of the Email.php file and information exfiltrated from users during the phishing attack that are sent to:
techhome18[@]gmail[.]com
we.us1[@]protonmail[.]com

Although the identity of the attacker behind this IRS phish is unknown, it is evident they took care to carefully craft this attack and chose to exploit a current event that is closely followed by Americans in an attempt to successfully steal as many log-in credentials as possible.

Network IOC IP
hxxp://playdemy[.]org/office/doc-new 206[.]123[.]154[.]15

 

 

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