The Rising Pattern 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 without 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 consequence of a characteristic that enables customers to connect recordsdata to OneNote paperwork it makes them a great 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 

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

 Primarily based on the telemetry from our endpoints now we 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 under.  The malicious doc is delivered in both zip recordsdata or ISO photographs to the goal by means of phishing emails. We’ve got noticed that a lot 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. These kind of 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 know how the information is specified by the file, we have to study it at byte stage. Taking a detailed have a look at OneNote doc offers us an fascinating remark as its magic bytes for the header just isn’t a trivial one. Determine 5 exhibits the primary 16 bytes of the doc binary. 

The primary 16 bytes must 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 exhibits header data taken from the OneNote specification doc. 

The Information Stream in OneNote, Say Whats up To FileDataStoreObject 

To seek out the embedded knowledge 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 under: 

• 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 knowledge within the OneNote doc. The dimensions could 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 information object is highlighted in yellow and the information is proven in pink. 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 now we have an thought of what the information object is, with this information we will automate the method of extracting embedded artifacts for additional evaluation from the OneNote doc by following the under 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  

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

By analyzing quite a few malicious paperwork, now we have 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. 

Qakbot Marketing campaign 1: 

This part accommodates particular particulars on a Qakbot marketing campaign. In marketing campaign 1, the malware writer 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 Move: 

• 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 pretend 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 pretend 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 accommodates obfuscated script as proven under: 

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

• 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 under: 

• 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.

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

Determine 18 exhibits 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 inside the doc. The message above the ‘Open’ button instructs the consumer to “double click on” with a view to obtain the attachment.

A better have a look at the doc reveals the graphical parts are all photographs positioned in a layered fashion by the malicious actor. By transferring 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. 

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’ll 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 under.  

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 the case of 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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