June 2025 APT Attack Trends Report (South Korea)
Overview
AhnLab has been using AhnLab Smart Defense (ASD) to monitor advanced persistent threat (APT) attacks against targets in Korea. This report will cover the types and statistics of APT attacks in Korea during June 2025 as well as features for each type.
Figure 1. June 2025 statistics on APT attacks in Korea
Most APT attacks identified in Korea were spread through spear phishing. In June 2025, LNK file-based spear phishing attacks were the most prevalent, while those using Hangul Word Processor (HWP) files also saw an increase compared to the previous month.
Trends of APT Attacks in Korea
The cases and features for each APT attack type identified in June 2025 are as follows.
1) Spear Phishing
Spear phishing is a type of phishing attack against specific individuals or groups. Unlike ordinary phishing attacks, the threat actor conducts reconnaissance before launching the attacks to collect information on and learn about the attack targets. Because the threat actor crafts phishing emails using the collected information, the recipients of the emails are highly likely to believe that they are from a trusted source. There are also cases where the sender’s address is manipulated through email spoofing. Most spear phishing attacks include malicious attachments or links that are intended to lure the user to open them.
Types distributed using this technique are as follows.
1.1. Attacks Using LNK Files
Type A
This type involves creating a compressed CAB file containing multiple malicious scripts to exfiltrate information and download additional malware. The distributed LNK file contains a malicious PowerShell command, which is used to extract the data of the CAB file and decoy document inside the LNK file, creating them on the user’s PC. The CAB file is then decompressed, and multiple script files (bat, ps1, vbs, etc.) included inside are executed. The executed script files can perform malicious behaviors such as exfiltrating information from the user’s PC and downloading additional files.
The confirmed file names are as follows.
|
File Name |
| Signal Marketplace Transaction History Verification and Feedback Submission Form_20250617.docx.lnk |
| Preliminary Opinion on Allowing Corporate Accounts for Virtual Asset Exchanges (CoinMarket).hwp.lnk |
| Instructions on Submitting Proof Documents Related to KB Bank Transfer and Transaction History (20250622).hwp.lnk |
| Instructions on Submitting Proof Documents for KB Bank Transfer and Transaction Details (20250625).hwp.lnk |
| Guide to Submitting Materials for Identifying the Source of Undeclared Funds (Enforcement Decree of the Value-Added Tax Act).hwp.lnk |
| Guide to Submitting Data to Identify the Source of Undeclared Funds.hwp.lnk |
| Cryptocurrency Receiving Confirmation.docx.lnk |
| Lim**_15-year Career Technical Skills and Resume_20250521.docx |
Table 1. Confirmed file names
In some of these LNK distribution cases, the compressed file contained both the LNK file and a legitimate document. The legitimate document is as follows.
Figure 2. Legitimate document included in the compressed file
Figure 3. Legitimate document included in the compressed file
Type B
This type executes RAT malware. They are generally distributed as compressed files alongside legitimate files. The LNK files found in distribution contained malicious PowerShell commands. The malware either downloads using DropBox API or Google Drive, or creates additional script files and obfuscated RAT malware in system folders like “%PUBLIC%” on the user’s PC. The RAT malware executed in the end can perform various malicious behaviors, such as keylogging and taking screenshots, according to commands from the threat actor. XenoRAT and RokRAT were some of the RAT types found in this case.
The confirmed file names are as follows.
|
File Name |
| National Intelligence Service and Investigation.docx |
Table 2. Detected file names
Below are decoy files that were used to deceive the user into thinking they executed a legitimate file.
Figure 4. Confirmed decoy file
