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The Rising Pattern of OneNote Paperwork for Malware supply

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Authored By Anandeshwar Unnikrishnan,Sakshi Jaiswal,Anuradha M 

noticed a brand new Malware marketing campaign which used malicious OneNote paperwork to entice customers to click on on an embedded file to obtain and execute the Qakbot trojan. 

OneNote is a Microsoft digital pocket book software that may be downloaded at no cost. It’s a note-taking app that permits collaboration throughout organizations whereas enabling customers to embed recordsdata and different artifacts. It’s put in by default in Microsoft Workplace 2021 and Microsoft 365.   

Malicious Actors are at all times looking for new methods in to contaminate their victims. Reminiscent of their shift to LNK recordsdata after Microsoft launched a coverage change disabled workplace macros by default. As a consequence of a characteristic that permits customers to connect recordsdata to OneNote paperwork it makes them different to LNK recordsdata as distribution automobile to deploy their malware. This weblog accommodates evaluation on how OneNote paperwork are used malicious and two particular campaigns that made use of OneNote paperwork to obtain and execute the Qakbot malware.  

OneNote Campaigns within the wild 

Figure 1 Campaign Heatmap
Determine 1 Marketing campaign Heatmap

Determine 1  exhibits the geo smart distribution of McAfee clients detecting malicious OneNote recordsdata. 

 Primarily based on the telemetry from our endpoints we’ve got recognized the next risk households deployed by OneNote paperwork: 

  • Iceid 
  • Qakbot
  • RedLine
  • AsyncRat
  • Remcos
  • AgentTesla
  • QuasarRAT
  • Netwire
  • Formbook
  • Doubleback 

Overview Of Malicious OneNote Paperwork 

A holistic view of the phishing campaigns that weaponize OneNote doc is proven in Determine 2 beneath.  The malicious doc is delivered in both zip recordsdata or ISO photographs to the goal by phishing emails. We have now noticed that many of the malicious paperwork both have Home windows batch script that invokes Powershell for dropping the malware on the system or Visible Fundamental scripts that does the identical.

Determine 2 Marketing campaign Overview

The generic theme of the email is invoice or authorized associated. A majority of these themes usually tend to be opened by the vicim. An instance electronic mail physique and attachment is proven in Determine 3 and 4. 

Determine 3 E-mail Physique
Determine 4 Attachment

A Deep Dive into OneNote File Format 

File Header 

To grasp how the info is specified by the file, we have to look at it at byte stage. Taking a detailed have a look at OneNote doc offers us an attention-grabbing remark as its magic bytes for the header shouldn’t be a trivial one. Determine 5 exhibits the primary 16 bytes of the doc binary. 

Determine 5 OneNote Header

The primary 16 bytes should be interpreted as GUID worth {7B5C52E4-D88C-4DA7-AEB1-5378D02996D3}. We are able to use the official documentation for OneNote specification to make sense of all of the bytes and its structuring. Determine 6 exhibits header info taken from the OneNote specification doc. 

Determine 6 OneNote Specification

The Knowledge Stream in OneNote, Say Hiya To FileDataStoreObject 

To search out the embedded knowledge in a OneNote doc, we have to be taught extra concerning the FileDataStoreObject which has a GUID worth of {BDE316E7-2665-4511-A4C4-8D4D0B7A9EAC}. The construction that holds the info is proven beneath: 

  • guidHeader (16 bytes) 
  • Measurement: 16 bytes 
  • Worth: {BDE316E7-2665-4511-A4C4-8D4D0B7A9EAC} 
  • cbLength 
  • Measurement: 8 bytes 
  • Worth: Measurement of the info 
  • unused 
  • Measurement: 4 bytes 
  • reserved 
  • Measurement: 8 bytes 
  • FileData 
  • Measurement: Variable 
  • guidFooter 
  • Measurement: 16 bytes 
  • Worth: {71FBA722-0F79-4A0B-BB13-899256426B24} 

The FileData member of the FileDataStoreObject is the important thing member that holds the embedded knowledge within the OneNote doc. The dimensions may be retrieved from the cbLength member. 

Determine 7 exhibits the “on disk” illustration of the FileDataStoreObject  That is taken from a malicious OneNote doc used to unfold the Qakbot payload. The guidHeader for the info object is highlighted in yellow and the info is proven in crimson. As it’s evident from the picture the info represents a textual content file which is a script to launch PowerShell.  

Determine 7 Embedded knowledge in Knowledge object

For extra info on the OneNote specification, go to reference part  

Artifact Extraction  

Now we’ve got an concept of what the info object is, with this information we will automate the method of extracting embedded artifacts for additional evaluation from the OneNote doc by following the beneath algorithm. 

  • Seek for FileDataStoreObject GUID within the binary. 
  • Interpret the FileDataStoreObject construction  
  • Retrieve cbLength member (measurement of the info represented by FileDataStoreObject) 
  • Learn N bytes (cbLength) after Reserved 8 bytes in FileDataStoreObject. 
  • Dump the bytes learn on to disk 
  • Repeat above steps for each FileDataStoreObject current within the binary

Embedded Executable Objects In OneNote  

Execution Of Embedded Entities  

Wanting on the runtime traits of OneNote Desktop software we’ve got noticed that when an embedded file will get executed by the consumer, it’s saved briefly within the OneNote listing within the Consumer’s Temp location. Every listing with GUID values represents a special doc opened within the OneNote software. 

Determine 8 OneNote listing in Temp

By analyzing quite a few malicious paperwork, we’ve got been in a position to create a “take a look at” OneNote doc that executes a batch file that accommodates the “whoami” command. The picture in Determine  9 present the batch file being created within the consumer’s temp location. 

Determine 9 OneNote drops embedded artifacts in Temp listing

Qakbot Marketing campaign 1: 

This part accommodates particular particulars on a Qakbot marketing campaign. In marketing campaign 1, the malware creator used phishing emails to ship malicious OneNote doc both as attachment or a URL hyperlink to zip file containing the OneNote doc. The OneNote contained aHTA file that when executed would make use of  the curl utility to obtain Qakbot after which execute it. 

An infection Circulation: 

Determine 10 An infection Chain
  • Spam electronic mail delivers a malicious OneNote file as an attachment or a hyperlink to a ZIP file that accommodates a OneNote file. 
  • OneNote file accommodates an embedded HTA  attachment and a faux message to lure customers to execute the HTA  file 
  • The HTA file makes use of curl utility to obtain the Qakbot payload and is executed by rundll32.exe. 

Technical Evaluation: 

The OneNote file with the embedded HTA file is proven within the Determine 11. As soon as this OneNote file is opened, it prompts the consumer with a faux message to double-click on open to view the attachment. 

Determine 11 OneNote Template

Upon clicking the Open button, it drops the HTA file with the identify Open.hta to the %temp% Folder and executes it utilizing mshta.exe. 

Determine 12 Drop file in Temp location

The HTA file accommodates obfuscated script as proven beneath: 

Determine 13 Obfuscated HTA script

The HTA file is loaded by MSHTA and creates a registry key in HKEY_CURRENT_USERSOFTWARE with obfuscated content material as proven beneath: 

Determine 14 Registry key creation
  • The obfuscated registry is then learn by MSHTA and the obfuscated code is de-obfuscated. The code is then initialized to a brand new operate object as proven in Block1. 
  • Lastly, MSHTA calls this operate by passing the malicious URL as a parameter after which deletes the registry key as proven in Block 2.

De-obfuscated content material from the HTA file is proven beneath: 

Determine 15 Deobfuscated HTA content material
  • Curl is used to obtain the malicious DLL file in C:ProgramData Folder with .png extension. The script will then execute the downloaded file with Rundll32.exe with the export operate Wind.
Determine 16 Downloaded payload in ProgramData
  • A faux error message is displayed after loading the downloaded payload and MSHTA is terminated.  
Determine 17 Pretend error message

Determine 18 exhibits the  

Determine 18 Course of Chain


Kind  Worth  Product  Detected 
Campain 1 – OneNote File  88c24db6c7513f47496d2e4b81331af60a70cf8fb491540424d2a0be0b62f5ea  Complete Safety and LiveSafe  VBS/Qakbot.a 
Campain 1 – HTA File  e85f2b92c0c2de054af2147505320e0ce955f08a2ff411a34dce69c28b11b4e4  Complete Safety and LiveSafe  VBS/Qakbot.b 
Campain 1 – DLL File  15789B9b6f09ab7a498eebbe7c63b21a6a64356c20b7921e11e01cd7b1b495e3  Complete Safety and LiveSafe  Qakbot-FMZ 

Marketing campaign 2: 

Inspecting Malicious OneNote Paperwork 

The OneNote doc for marketing campaign 2 is proven in Determine 19. At first look it it seems that there’s a ‘Open’ button embedded inside the doc. The message above the ‘Open’ button instructs the consumer to “double click on” with the intention to obtain the attachment.

Determine 19 Malicious content material

A more in-depth have a look at the doc reveals the graphical components are all photographs positioned in a layered model by the malicious actor. By shifting the icons apart, we will see the malicious batch file which when executed downloads the payload from the Web and executes on the goal system. 

Figure 20 Hidden Malicious dropper script
Determine 20 Hidden Malicious dropper script

Execution Of Payload Dropper 

Upon execution of the batch file, Powershell will likely be invoked and it fetch the Qakbot payload from Web and execute it on the goal system. This part will cowl particulars of dropper script used to deploy QakBot. The Determine 21 Present the method tree after the execution of the script and you may see that powershell.exe was launched by cmd.exe and the dad or mum of cmd.exe is onenote.exe. 

Determine 21 Course of chain

The contents of course of cmd.exe (7176) are proven beneath.  

Determine 22 Cmd.exe properties

The base64 decoded batch file is proven in Determine 23This can use powershell to obtain the payload after which execute it with rundll32.exe

Determine 23 Base64 Decoded directions in dropper


Kind  Worth  Product  Detected 
Campain 2 – Zip File  000fb3799a741d80156c512c792ce09b9c4fbd8db108d63f3fdb0194c122e2a1 


Complete Safety and LiveSafe  VBS/Qakbot.a 
Campain 2 – OneNote File  2bbfc13c80c7c6e77478ec38d499447288adc78a2e4b3f8da6223db9e3ac2d75  Complete Safety and LiveSafe  One/Downloader.a 
Campain 2 – Powershell File  b4dd3e93356329c076c0d2cd5ac30a806daf46006bdb81199355952e9d949424  Complete Safety and LiveSafe  PS/ 
Campain 2 – OneNoteFile  a870d31caea7f6925f41b581b98c35b162738034d5d86c0c27c5a8d78404e860   Complete Safety and LiveSafe  VBS/Qakbot.a 



Malware authors are getting extra refined with regards to hiding their payloads. This Weblog highlights the latest Qakbot marketing campaign that delivers its payload which makes use of the OneNote software as a supply mechanism. McAfee Clients ought to hold their methods up-to-date and chorus from clicking hyperlinks and opening attachments in suspicious emails to remain protected. 




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