ASEC Weekly Phishing Email Threat Trends (December 11th, 2022 – December 17th, 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 11th, 2022 to December 17th, 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 Infostealer, taking up 54%. Infostealer includes malware such as AgentTesla and FormBook, and they leak user credentials saved in web browsers, emails, and FTP clients.

It was then followed by downloader (21%), which includes loaders such as Amadey, BeamWinHTTP, and SmokeLoader. Downloaders can receive commands from the attacker to download additional malware, and when info-stealing modules are used, it can collect user credentials in the infected system.

The third most prevalent type was fake login pages (FakePage), which took up 11%. 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

Aside from these, Backdoor (7%), Worm (4%), and Exploit (3%) 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 11th, 2022 to December 17th, 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
Fwd: el documento adjunto y haga la correccion – factura pendiente (20****) Comprobante – 2022-12-13T******.520.html
New Order – Please send proforma invoice P.O0076.html
Payment Advise Payment Slip.html
RE: 316863-52 order 394620 RE 316863-52 order 394620.html
Re: Contract Invoice contract_agremt528 PM.html
URGENT: Upgrade E-mail User Mailbox Upgrade.html
Confirmation of Bank Payment ______HKU-COMPFEE-0000708718.htm

Case: Malware (Infostealer, Downloader, etc.)

Email Subject Attachment
pago noviembre-diciembre Pago1292022.img
RE: Statement of account MBS Statement of account MBS.img
Re: pago rechazado de Banco Banamex SA de CV (Ref 0180066743) Aviso de pago.pdf.img
PAYMENTS – 12th December 2022 international_transfer_20221212-21617.pdf.gz
DHL AWB – 4152209227 DHL AWB – 4152209227_12132022.gz
TT (Ref 001122022066743) Ref001122022066743.img
PO #20221412042 Purchase Order #20221412042.zip
TT (Ref 001122022066743) Ref001122022066743.img
PO #20221412042 Purchase Order #20221412042.zip
NEW ORDER #306078910 P.O #306078910.xls
Re: D/N: Ex-work PO#22-1652/63, PO#22-4982/68, PO#22-1264/69
AAA PO22165263 PO22498268 PO22126469 DEBIT NOTES.xls
Fwd: PL/ DS_CMR 81364970 DS_CMR 81364970.pdf.img
Re: Revised proforma invoice & Contract payment for- ifeoluwa.babarinsa PI-202510145-dtd-13-12-2022.img
RFQ #20220812 Order 0092300 Quote PO# 000938812.pdf(45kb).img
RV: OFERTA PO# 000938812 PO# 000938812.pdf(45kb).img
Re: Invoice Request ( Dec’22 ) Bank Outward Application.PDF.zip
Re: D/N: Ex-work PO#22-1652/63, PO#22-4982/68, PO#22-1264/69
PO22165263_PO22498268_PO22126469_DEBIT_NOTE_TT.PDF.rar
Dhl -Express_Shipping Original Document Shipping_Original_Document.PDF.7z
order 33690120220531MES_S Quote.img
STAINING ON THE BODY FABRIC OF STYLE VOLTO II bank information.exe
DHL AWB & Shipping Document: Invoice JKTR002071488. DHL AWB and Shipping Document.pdf.tar
order Quote_2200001498.img
RE: CONTRACT 2023 – nyaonjs.com -OB OG 2023.pdf.iso
Re: New order New order 4311.xz
Re: New order New order 4311.zip
Quotation, Enquiry (RFQ) 2200111 RFQ 2200111.PDF.GZ
Order For Dec E900 quotation20111388.img
Request for Price ( PO# 205346 ) Request for Price PO# 205346.PDF.GZ
Hesap hareketleriniz Hesaphareketi-01.tar
DHL Shipment Notification Dhl p.gz
Re: Shipping document EXP4052
MSKD0134772_MAERSK_AMAZON_INV20221211_Pdf.rar
STAINING ON THE BODY FABRIC OF STYLE VOLTO II bank information.exe
DHL AWB & Shipping Document: Invoice JKTR002071488. DHL AWB and Shipping Document.pdf.tar
order Quote_2200001498.img
RE: CONTRACT 2023 – nyaonjs.com -OB OG 2023.pdf.iso
Re: New order New order 4311.xz
Re: New order New order 4311.zip
Quotation, Enquiry (RFQ) 2200111 RFQ 2200111.PDF.GZ
Order For Dec E900 quotation20111388.img
Hesap hareketleriniz Hesaphareketi-01.tar
DHL Shipment Notification Dhl p.gz
smart pics privateplp.gif.exe
wonderful pictures theaction.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:Factura’ andOrder’

Keywords of this week are ‘Factura’ and ‘Order.’ These two keywords appeared in 38% of phishing email subjects, which is considerably high. ‘Order’ and ‘Factura’ (meaning ‘Invoice’) are often used in transactions, and the threat actor impersonated certain companies to distribute malware. The following case attached an HTML file to the email. The attachment is a phishing file (FakePage) disguised as a login page.

Next is an IMG file, which was most often seen.

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://formspree.io/f/mlevkpjv
  • hxxps://womeninpublishing.org/wp-admin/RFxData/mstpartsgroup.php
  • hxxps://alxcl.xyz/log-flasher/excel.php
  • hxxps://frwx.ml/anydomain/anydomain.php
  • hxxps://www.1dglabel.com/wp-content/COMPFEE/next.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])

Subscribe to AhnLab’s next-generation threat intelligence platform ‘AhnLab TIP’ to check related IOC and detailed analysis information.

Categories:Statistics

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