Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 8a290720c5ebde60…

MALICIOUS

Office (OOXML)

440.1 KB Created: 2000-04-13 21:48:14 UTC Authoring application: Microsoft Excel 12.0000
MD5: 8cd2f57e863747dd11f0e2ae145e93c4 SHA-1: c11c8901a932ef10188605f505c89ab47cb589e4 SHA-256: 8a290720c5ebde60974b2854a21cf0b2d2c4cfc594e49261d6443382ebd079dd
208 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059 Command and Scripting Interpreter T1204.002 Malicious File

The sample contains a Workbook_Open macro that is heavily obfuscated and uses CreateObject to execute a script. The script is constructed from concatenated strings and environmental variables, ultimately leading to the execution of 'mshta C:\Users\Public\getBarStacked1003992.sct'. This indicates the macro's purpose is to download and execute a second-stage payload.

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
dd2d6d1ec9a9b18864836cabe0d463de99baa5addc40ae7c685a4e7402383be1		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 1114 bytes
vbaProject_00.bin
bd6e212153abf37c19d1a7b437719bf0f5b48c59d29a09e8c2017e6938e04d3f		 vba-project OOXML VBA project: xl/vbaProject.bin 9216 bytes

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