ASEC Weekly Phishing Email Threat Trends (December 4th, 2022 – December 10th, 2022)

The ASEC analysis team monitors phishing email threats with the ASEC automatic sample analysis system (RAPIT) and Honeypot. This post will cover the cases of distribution of phishing emails during the week from December 4th, 2022 to December 10th, 2022 and provide statistical information on each type. Generally, phishing is cited as an attack that leaks users’ login account credentials by disguising as or impersonating an institute, company, or individual through social engineering methods. On a broader note, the act is a technical subterfuge that enables the threat actor to perform attacks such as information leaks, malware distribution, and fraud against various targets. The focus of this post will be on the fact that phishing attacks mainly occur through emails. We will also provide a detailed classification of various attack methods that are based on phishing emails. Furthermore, we will make an effort to minimize user damage by introducing new attack types that have never been found before and emails that require users’ caution, along with their keywords. The phishing emails covered in this post will only be those that have attachments. Emails that have malicious links in the body without attachments will be excluded. Additionally, the type that leaks login account credentials will be defined as FakePage.

Phishing Emails

During this week, the most prevalent threat type seen in phishing email attachments was FakePage, taking up 36%. FakePages are web pages where the threat actor has imitated the screen layout, logo, and font of the real website, leading users to enter their account and password information. The input information is sent to the threat actor’s C2 server.See <Fake Login Page C2> below

The second most threat type was Infostealer with 23%. Infostealer includes malware such as AgentTesla and FormBook, and they leak user credentials saved in web browsers, emails, and FTP clients.

The third treat was followed by downloader (16%), which includes loaders such as SmokeLoader and GuLoader. Aside from these, Worm (13%), Backdoor (7%), Trojan (3%), and Exploit (2%) types were detected.

The threat types using phishing email attachments and their order of prevalence are similar to the order of malware distribution published weekly in the <ASEC Weekly Malware Statistics>.

File Extensions in Phishing Emails

We have identified which file extensions were used by the threats above for the distribution of email attachments. As FakePages are web page scripts that must be executed with a web browser, they were distributed with HTML and HTM file extensions. Other malware, including Infostealer and downloader, came attached to emails with various file extensions including compressed files (ZIP, R00, RAR, 7Z, etc.), IMG disk image files, and XLS document files. With the exception of fake login pages which have to be web page script files, other malware types were distributed with a variety of file extensions regardless of the threat type. Among the phishing email attachment types, the IMG file variant showed a particularly high percentage.


Cases of Distribution

The following are distribution cases that occurred during the week from December 4th, 2022 to December 10th, 2022. The cases will be classified into fake login pages and malware types, including Infostealer, Downloader, Exploit, and Backdoor. The numbers in email subjects and attachment filenames are unique IDs and may vary depending on the email recipient. Distribution cases with Korean subjects were also found. These are cases that specifically targeted Korean users instead of propagating themselves globally using the identical English subject and text.

Case: Fake Login Pages (FakePage)

Email Subject Attachment
4_DHL KOREA sent you a [Statement of Transaction]. AWB-87466784.html
FW: Quotation Enquiry.html
Payment Advise Payment Slip.html
Please approve payment of attached invoice before we process payment invoice balance payment comfirmation pdf.htm
RE: Shipping docs PO 2211& 785521 -Draft invoice comfirmation shipping docs invoice BL comfirmation pdf.htm
Your parcel has arrived urgent pick up needed today.? DHL AWB #8347630120622.pdf.htm
Case: Malware (Infostealer, Downloader, etc.)
Email Subject Attachment
20220512 Order 00177 20220512 Order 00177.pdf (78kb).img
TT05122022 Updated Payment List – 2022.12.05 Re: Contract for PO064005 TT0512202201.img
RFQ12072022 RFQsheet12072022.rar
Fw: RFQ#223090 Request quotation RFQ 223090.PDF.7z
RE: BALANCE PAYMENT Swift Copy.img
NEW ORDER #306078910 P.O #306078910.xls
CIF_ MW1000CW (NEW) QUOTATION CIF_ MW1000CW (NEW) QUOTATION.r00
Re[5]: very wonderful pictures imortant prv-photos.exe
RE: WRONG IBAN/PAYMENT RETURNED Transfer Application.img
Re: nuevo pedido #lista de precios y menor tiempo de entrega lista de cotizaciones.img
very cool images imortant sex_img.gif.pif
beautiful pictures superact.exe
RE: NEW ORDER PI IMG09122201.img
smart pics coolaction.gif.exe
Re[5]: beautiful photos privaction.jpg.pif
Re[2]: super cool picture PRIVATE best__action.jpg.pif
Re: RETURN PAYMENT TT (Ref 0180066743) TT12052022.img
PO No. ANOP0658 PO_No._ANOP0658.img
cool pictures only for you sexphotos.jpg.exe

The ASEC analysis team has selected keywords that users must look out for, based on the distribution cases above. If these keywords are included in the subject of the email, or if the same characteristics are found, users must exercise strict caution as they may be phishing emails from threat actors.

Keywords to Beware of: Statement of Transaction’
Among phishing emails, there were emails using the ‘Statement of Transaction’ keyword to impersonate certain companies and distribute malware strains. The following case attached an HTML file to the email. The attachment is a phishing page (FakePage) disguised as a login page.
Keywords to Beware of: ‘PIF’ Disguised as Image Files
The Worm-type malware disguised as image files has been found among phishing email types. As shown below, the file was distributed with the extension pif. This is an executable file just like the EXE extension.

Fake Login Page (FakePage) C2 URL

When users enter their IDs and passwords on the fake login page created by the threat actor, their information is sent to the attacker’s server. The list below shows the threat actor’s C2 addresses of fake login pages distributed during the week.

  • hxxps://reverse-nature.mymeriva.com/.well-known/pki-validation/exe.php
  • hxxps://formspree.io/f/mlevkpjv
  • hxxps://satursuions.cc/MOyhoia/feedback.php
  • hxxps://submit-form.com/FgKiWexJ
  • hxxps://gojobs.in/xzx/dhl.php

Preventing Phishing Email Attacks

Attacks using phishing emails are disguised with content that can easily deceive users, such as invoices and tax payments, to induce users to access fake login pages or execute malware. Fake login pages are evolving by the second to closely resemble the original pages. The attackers pack malware in compressed file formats to escape the attachment scans of users’ security products. Users must practice strict caution and refer to recent cases of distribution to avoid being exposed to infection by malicious phishing emails. The ASEC analysis team recommends users follow the email security guidelines below.

  • Do not execute links and attachments in emails from unverified senders until they are proven to be credible.
  • Do not enter sensitive information such as login account credentials until the site is found to be reliable.
  • Do not execute attachments with unfamiliar file extensions until they are found to be reliable.
  • Use security products such as antimalware software.

According to the MITRE ATT&CK framework, phishing email attacks correspond to the following techniques.

  • Phishing for Information (Reconnaissance, ID: T1598[1])
  • Phishing (Initial Access, ID: TI1566[2])
  • Internal Spearphishing (Lateral Movement, ID:T1534[3])

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Categories:Statistics

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