The Rising Development of OneNote Paperwork for Malware supply

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 utility that may be downloaded at no cost. It’s a note-taking app that enables 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. Comparable to their shift to LNK recordsdata after Microsoft launched a coverage change disabled workplace macros by default. As a result of a characteristic that enables customers to connect recordsdata to OneNote paperwork it makes them a very good different to LNK recordsdata as distribution car to deploy their malware. This weblog incorporates 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 

Determine 1  reveals the geo clever distribution of McAfee prospects detecting malicious OneNote recordsdata. 

 Primarily based on the telemetry from our endpoints we now have recognized the next menace households deployed by means of OneNote paperwork: 

• Iceid 
• Qakbot
• RedLine
• AsyncRat
• Remcos
• AgentTesla
• QuasarRAT
• XWORM
• 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 pictures to the goal by means of phishing emails. We’ve got 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 Primary scripts that does the identical.

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

A Deep Dive into OneNote File Format 

File Header 

To grasp how the information is specified by the file, we have to study it at byte degree. Taking an in depth take a look at OneNote doc provides us an fascinating statement as its magic bytes for the header shouldn’t be a trivial one. Determine 5 reveals the primary 16 bytes of the doc binary. 

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

The Information Stream in OneNote, Say Howdy To FileDataStoreObject 

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

• guidHeader (16 bytes) 
• Measurement: 16 bytes 
• Worth: {BDE316E7-2665-4511-A4C4-8D4D0B7A9EAC} 
• cbLength 
• Measurement: 8 bytes 
• Worth: Measurement of the information 
• 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 information within the OneNote doc. The scale might be retrieved from the cbLength member. 

Determine 7 reveals 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 information object is highlighted in yellow and the information is proven in crimson. As it’s evident from the picture the information represents a textual content file which is a script to launch PowerShell.  

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

Artifact Extraction  

Now we now have an thought of what the information object is, with this data we are able to 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 (dimension of the information 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  

Trying on the runtime traits of OneNote Desktop utility we now have noticed that when an embedded file will get executed by the consumer, it’s saved briefly within the OneNote listing within the Person’s Temp location. Every listing with GUID values represents a unique doc opened within the OneNote utility. 

By analyzing quite a few malicious paperwork, we now have been capable of create a “check” OneNote doc that executes a batch file that incorporates the “whoami” command. The picture in Determine  9 present the batch file being created within the consumer’s temp location. 

Qakbot Marketing campaign 1: 

This part incorporates 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 Movement: 

• Spam electronic mail delivers a malicious OneNote file as an attachment or a hyperlink to a ZIP file that incorporates a OneNote file. 
• OneNote file incorporates 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. 

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

The HTA file incorporates obfuscated script as proven beneath: 

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

• The obfuscated registry is then learn by MSHTA and the obfuscated code is de-obfuscated. The code is then initialized to a brand new perform object as proven in Block1. 
• Lastly, MSHTA calls this perform 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: 

• 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 perform Wind.

• A faux error message is displayed after loading the downloaded payload and MSHTA is terminated.  

Determine 18 reveals the  

IOCs: 

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 throughout the doc. The message above the ‘Open’ button instructs the consumer to “double click on” as a way to obtain the attachment.

A better take a look at the doc reveals the graphical parts are all pictures positioned in a layered type by the malicious actor. By transferring the icons apart, we are able to see the malicious batch file which when executed downloads the payload from the Web and executes on the goal system. 

Execution Of Payload Dropper 

Upon execution of the batch file, Powershell will probably 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. 

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

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

 IOCS 

Domains: 

starcomputadoras.com 

Conclusion: 

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

 References: 

https://be taught.microsoft.com/en-us/openspecs/office_file_formats/ms-onestore/405b958b-4cb7-4bac-81cc-ce0184249670 

https://be taught.microsoft.com/en-us/openspecs/office_file_formats/ms-onestore/8806fd18-6735-4874-b111-227b83eaac26 

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