HWP documents are primarily associated with the Hangul Word Processor software used in South Korea. 

Hackers may opt for HWP documents to target National Defense and Press Sectors because they exploit vulnerabilities in this specific file format and software, which may not be as widely monitored or protected as more common document formats like PDF or Microsoft Word.

Cybersecurity analysts at ASEC recently discovered HWP documents with OLE objects, potentially distributed via email attachments or download links, targeting specific sectors like:-

The document names relate to the following domains:-

  • National Defense
  • Unification
  • Education
  • Broadcasting

Hackers Weaponize HWP Documents

The analyzed HWP documents have two main types:-

  • One connecting to an external URL.
  • The other one creating a script file. 

However, the researchers also suspect a common creator due to the shared FTP server password in type 2.

Operation process (Source - ASEC)
Operation process (Source – ASEC)

Here below, we have mentioned all the HWP documents’ file names:-

  • Unification** cue sheet May 29 Mon.hwp
  • 20230508_ProfessorMeetingMaterial_NewTemplate.hwp
  • (***)2023-05-30 Material for Professor Meeting.hwp
  • Payment Receipt (Chief ***).hwp
  • (Template)Payment Receipt_Congratulatory and Condolence Money.hwp
  • 20230512_MyungbakScenario_Details.hwp
  • 1-1.Installation of a Separate Service for Research Support Within the Overseeing Organization (** University Graduate School Academic-Industry Cooperation Center).hwp
  • Reference Material for School President for the Honorary Doctorate Awarding Ceremony of Former Prime Minister Hu** ***.hwp
  • [Faculty Training Department-489 (Attached)] [Attachment 3] Lecturer Card (Template).hwp
  • National Defense and Protection Sacrificed to Political Disputes.hwp
  • ** Unification April 30 2023 (Sun).hwp
  • Special The Agricultural Industry and Quality of Life of North Korea ** Cho.hwp
  • 42- Wagner’s Lesson (Aug 2023).hwp
  • [Template1] Business Budget Issue Request.hwp
  • Dissertation Evaluation (** Kwon).hwp
  • Evidentiary Documents of Incentive Payment.hwp
  • ** Unification Sep 06 Final Wednesday.hwp
  • ** Kim_Statement of Honorarium Payment.hwp
  • [Template_Attachment 5]_Recommender_Certificate_Template-** Jeon.hwp

The OLE object has 5MB of dummy bytes and a malicious URL. When clicked, it connects to that URL, and the malicious URLs found are tailored for specific individuals with unique parameters.

Here below, we have mentioned the malicious URLs:-

  • hxxp://host.sharingdocument[.]one/dashboard/explore/starred?hwpview=[specific value] 
  • hxxp://mail.smartprivacyc[.]com/get/account/view?myact=[specific value]

Type 2 HWP docs embed a malicious script. It creates zz.bat and oz.txt in %temp%. Clicking them runs PowerShell commands from GitHub:-

  • hxxps://raw.githubusercontent[.]com/babaramam/repo/main/pq.txt

Besides this, the data is deobfuscated and executed with a key, while the GitHub script has four functions that we have mentioned below:-

  • mainFunc
  • getinfo
  • uploadResult
  • downCommand

The mainFunc changes the PowerShell policy, enabling later script execution. getinfo collects user data from hxxps://raw.githubusercontent[.]com/babaramam/repo/main/info.txt. 

uploadResult sends collected data and deletes it. downCommand maintains persistence with the LNK file. thumbs.log runs the script on PC restart.

Though it collects user data, the script can perform various malicious actions based on pq.txt.

Nowadays, there are multiple malicious HWP documents circulating actively, so it’s strongly recommended to be cautious about document authors and senders.

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