ASEC Weekly Phishing Email Threat Trends (May 28th, 2023 – June 3rd, 2023)

AhnLab Security Emergency response Center (ASEC) 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 May 28th, 2023 to June 3rd, 2023 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.

Phishing Emails

During this week, the most prevalent threat type seen in phishing email attachments was FakePage with 36%. FakePages are web pages where the threat actor has imitated the screen layout, logo, and font of the real login pages or advertising pages, leading users to enter their account and password information. The input information is sent to the threat actor’s C2 server or used to induce users to access other fake websites. See <FakePage C2>  below The second in line were Infostealers like AgentTesla, FormBook, and AveMaria that leak user credentials saved in web browsers, emails, and FTP clients (27%). Aside from these, Trojan (22%), Downloader (10%), Exploit (2%), Worm (1%), Backdoor (1%), and Dropper (1%) 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. FakePages were distributed through web pages script (HTM, HTML, SHTM, and SHTML) documents that must be executed with a web browser. Other malware, including Infostealer and downloader, came attached to emails with file extensions including compressed files (RAR, Z, GZ, 7Z, etc.).

Cases of Distribution

The following are distribution cases that occurred during the week from May 28th, 2023 to June 3rd, 2023. The cases will be classified into FakePage 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 identical English subjects and texts.

Case: FakePage

Email SubjectAttachment
[FedEx] Tariffs payment notice (Tax Invoice)FedEx.html
02-QT-000488 – Request for Price Q1-Project order specification requestPO-02-QT-000488 _**********.com.HTM
PO vkj production status MAY.29 T/Tpo~vkj_mfj3987365367893.pdf
Your account already has +14777$Your_balance_has_been_replenished_22%2C336%24-8615.pdf
When you get your money +16853$You_are_now_rich_21.639%24_on_your_balance-263.pdf
FW: RE: Shipping DocumentsScanned Bill of Lading Doc.Pdf.htm
Re: RFQ – 3~PHASE ORDPO-98802.shtml
Re: Balance payment confirmation cg06″Bal_payment swift.shtml
You are now rich +11498$ on your balance!26316%24_Need_to_move_you_have_24_hours-14255.pdf
Signed Shipping Documents For Consignee (********@********* Of Lading Copy.html
You are now rich +27244$ on your balance!When_you_get_your_money_17%2C612%24-2703.pdf
Come on, quickly withdraw your +27662$! The account is not blocked yet29%2C694%24_Need_to_move_you_have_24_hours-14275.pdf Invoice 8831882301lnvoice-8831882301.pdf Invoice 9831249301lnvoice-9831249301.pdf
Re: June/New-Order #Brazil-098484OBZJune_New-Order #Brazil-098484OBZ.XLS.html
[DHL] Shipping Document // Arrival-Notification – ETA: 6/25 BL NO: 23*******Shipping Document_Bill of Lading.Pdf.htm
Request for quotationQuote.htm
【电子发票号码:30940297】您收到一张新的电子发票SF E-Invoice 30940297.pdf.html
VERIFY YOUR **********.com ACCOUNT.*********.comUPDATE.shtml
New Order for Po No. : 4500250395PO2340943.html
<Request for Quotation> / Toyo Korea / ****** *** ElectricOrder345009.html
invoice & Shipping Documents 29 May 2023dhl-shipment_invoice PI-Bill Of Lading#998454.htm
Re:(Scanned) Doc~Original Copy – FYIShipping document.html
Shipment Notice – Confirm Shipping DocumentsScanned Copies of Packing List_ETD.Pdf.htm
MAY P.O _3000000821MAY P.O _3000000821.Shtm

Case: Malware (Infostealer, Downloader, etc.)

Email SubjectAttachment
Reply: Reply: [DHL] Acceptance of Import Declaration (Payment Before Acceptance) – 1000452436Import declaration acceptance statement-1000452436.rar
UPS Korea-att invoice contentatt1-Doc^^ICNIR00112339^^ACC^^KR^^IBS^^BIV_FRI_ICN.z
Final Warning – Over Due Payment – Urgent Reminder!Final Warning – Over Due Payment – Urgent R….Overdue.img
RE: BookingMSDS-112800.xlsm
P. Order & Contract (A-4553)2P. Order & Contract (A-4553)2.rar
New Order 220628001New Order 220628001.PDF.iso
[Sending Finalized Text] G7+Partners FASS Meeting[FINAL] ********* Action Statement for Resilient Global Food_ Security_trackchanged.docx
Pending DHL Shipment Notification REF: 02/6/2023Shipping doc.img
Enquiry for Quotation – Works at Sector MZW-18 in ****** ****** ProjectPO.028940.22.S-R224454676781-P0-MT_SAM.rar
Shipment Delivery Address *(Required) contact formRequired contact form..rar
Payment Receipt For T/T USD$140,378,00Payment Receipt For TT USD$140,378,00.rar
Please review your July 2022 offerPLAYGROUND PROJECT – 2022089928 – KDF.arj
RE: RE: FW: 2023/7/24 order shipmentAutomann- Order2#44096.docx
cargo booking to Maresk for Po SPL-036500 & SPL-037282SPL-036500 & SPL-037282.pdf.z
Fw: Copia de pagoCopia de pago#8101227910.05302023.gz
New enquiryQuotation Details_pdf.z
NEW ORDERPurchase Order 982F23.Docx.img
purchase orderPO331020770.z
Purchases Order // PO23100080PO23100080.z
quote requestPurchase order.r20
RE: inquiry30590120233540MES_S Quote.z
Re: Purchase Order No. 9455 & 95569455 & 9556.z
RE: quote request10690531TEZ_S Quote.r09
Re[5]: wonderful picsgreat_pctrs.pif
Ref:103XXXXX Shipment of Original Documents.DHL SHIPMENT NOTIFICATION_PDF.gz
*****Bank tarafindanevraklar.gz
very cool picturessex-pic.jpg.exe
RE ; Advance in process – project #1021 (30% deposit)invoice.xls
RE: Statement of AccountSOA.xls
RE: ReservationMSDS-19055205pdf.7z
RE: Booking RequestMSDS-112883pdf.7z
Re: “URGENT” PAYMENT BACK RETURNED TT (Ref 0066743)006673-001.arj
Re: Request for Quotation via ShipServ DQR02/5-10-2023QTN-DQR025-10-2023.rar
Payment Advice Note 81930 30.05.2023 – 4360APAYMENT COPY $79,
*** *** ****** New Order PO#HKPOORD002361-2362New Order
AW: PO-000001306PO-000001306.z
Certificates Of AnalaysisCertificates Of Analaysis.rar
Commercial and technical offerCommercial and technical offer.rar
Payment. (******* BANK ACCOUNT)INVOICE_VM33020031052023.IMG
Purchase Order PO-5093027bPO-5093027b.r02
RE: Offer RequestRE Offer Request.rar
Re: order33690120233531MES_S Quote.z
Request V-23-VJU-028-D/01 for the Voge JulieV-23-VJU-028-DGFGRz9eenOICt9Y-xlxs.rar
Signed Authorization letterSigned Authorization letter.rar
Urgent (TT draft copy)MT103-draft.r20
swift copyswift.LZ
RE: ****** SHIPPING COMPANYMSDS-112703pdf.7z
About the paymentRemittance Copy#0128762534.pdf.gz
DHL awb – 4026735019DHL awb – 4026735019_20230525.gz
Fw: Due Invoice Payment20230106.8203849061-mt103-Trf.gz

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.

Keyword to Beware of: ‘Invoice’

The keyword for this week is ‘Invoice.’ For this week, it has been confirmed that multiple emails were distributed with a Korean title (UPS Korea-att invoice content) and disguised as a certain transport company. The email was attached with a malicious file with the SCR extension. The file is an Infostealer that steals information by running the normal process aspnet_compiler.exe and injecting AveMaria into that normal process. Users must pay attention to the content of the email to check for any unfamiliar file attachment extensions and poorly translated Korean.

FakePage C2 URL

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

  • https[:]//submit-form[.]com/nv7B93q6
  • https[:]//www[.]spgiutar[.]com/mmc/fdpxoGur23f[.]php
  • http[:]//www[.]miassmebel-neo[.]ru/ZaZa/port25[.]php
  • https[:]//aphal[.]000webhostapp[.]com/acr/PDF
  • https[:]//submit-form[.]com/Lc0iCuYC
  • https[:]//cardiofitness[.]guru/maersk/mk[.]php
  • https[:]//submit-form[.]com/t5Rk3sUT
  • http[:]//vanchuyentrungviethhc[.]com/wp-admin/YSL/Daemon[.]php
  • https[:]//sercex[.]com/justgm[.]php
  • https[:]//formcarry[.]com/s/8AHxxLifK2
  • https[:]//submit-form[.]com/b8nhWuB2
  • https[:]//formspree[.]io/f/xrgvdwqd
  • https[:]//www[.]vvl-badvilbel[.]de/wp-content/plugins/3ae9ce9eaa8d4ce9a0f81e400863ce6b/y/mm/mdx/mmd/exee[.]php
  • https[:]//naehpa[.]com/wp-admin/QY/port25[.]php

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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