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

Static analysis result for SHA-256 648f3cfa84dcf8d3…

MALICIOUS

Office (OOXML) / .XLSM

437.8 KB Created: 2021-07-28 10:37:27 UTC Authoring application: Microsoft Excel 12.0000
MD5: ed7d4f522688d5fed0aa894635366d33 SHA-1: 30804923d77142957720941e9648252fbbd00263 SHA-256: 648f3cfa84dcf8d38e7dfb478761f6db74db1276c1f483ea8a14085965108d5b
208 Risk Score

Malware Insights

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

The sample is an XLSM file containing a Workbook_Open macro that is heavily obfuscated. The macro uses CreateObject to execute a command that involves mshta and a script file named '\getPatternLightVertical9955.sct'. This script is likely a second-stage payload designed to download and execute further malicious content. The use of Environ() and Cells() to construct paths and commands indicates an attempt to evade static analysis.

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
d640f836ed9b395f509c754677408165e1da47c0d0094a8376ce23ce9c46f9d0		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 1135 bytes
vbaProject_00.bin
b8c5066e7f48618cf3853584d79ebf74236535e515e7b6e4865dad37707dfad0		 vba-project OOXML VBA project: xl/vbaProject.bin 9216 bytes

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