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

Static analysis result for SHA-256 606179a861ee31ce…

MALICIOUS

Office (OOXML) / .XLSM

435.8 KB Created: 2021-07-28 10:37:27 UTC Authoring application: Microsoft Excel 12.0000
MD5: 8b69459558ae458def4c59d70d1ad4a9 SHA-1: 2601383d95e1fd16bb46d7c3a0ec86e33bbfb82a SHA-256: 606179a861ee31ce20f90bec1bed76e175789022918670acbf629a48320c0543
208 Risk Score

Malware Insights

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

The critical heuristic 'OLE_VBA_OBFUSCATED_AUTOEXEC_LOADER' indicates an obfuscated auto-exec VBA loader. The WorkBook_Open macro executes a command using CreateObject, which is used to download and execute a script file. The reconstructed command is 'mshta C:\Windows\System32\ALLUSERSPROFILE\getPaperFanfoldLegalGerman7664.sct', indicating the execution of a script downloaded from a potentially malicious source.

Heuristics 6

  • 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
  • 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.
  • VBA project inside OOXML medium OOXML_VBA
    Document contains a VBA project — VBA macros present
  • 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
b8c6d865280f438c7cef8bfbc60ec560c21ecdf9e8e0ecac943cbcaf9b8a7046		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 1127 bytes
vbaProject_00.bin
b4367e129c76fdeb78dc6f36eb3e9d47f737f7bc9f836731ced45b668f3c5ac9		 vba-project OOXML VBA project: xl/vbaProject.bin 9216 bytes

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