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

Static analysis result for SHA-256 06dc625ae496277f…

MALICIOUS

Office (OOXML) / .XLSX

145.4 KB Created: 2020-03-24 22:45:37 UTC Authoring application: Microsoft Excel 15.0300
MD5: 6bbee71945d3a42451c8a67d417232eb SHA-1: b92a6a767c4e460f9494c9303a0cfe73f4a2f9b7 SHA-256: 06dc625ae496277fa65350786d3a1abb03198af71fe9e6170d2c58b15f1ffb01
220 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment T1203 Exploitation for Client Execution

The file is an Excel document containing a Workbook_Open macro. This macro utilizes obfuscated VBA code, employing character shifting and concatenation, to execute a command via the Shell() function. The critical heuristics indicate auto-execution and the use of Shell() with character decoding, strongly suggesting the intent to download and execute a second-stage payload.

Heuristics 5

  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • VBA character-shift decoded Shell command critical OLE_VBA_ASC_CHR_SHIFT_SHELL
    VBA auto-exec macro stores an encoded command string, decodes it with a Mid/Asc/Chr character-shift loop, and passes the recovered text to Shell. This is a high-confidence command stager.
  • Workbook_Open macro high OLE_VBA_WBOPEN
    Workbook_Open macro
  • 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

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
9297bb7de01081ce1cf96cb815f2557efbcd0003ff0ee5a96b9a54ba988fbe23		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 2702 bytes
vbaProject_00.bin
4b7f477f71a0d48acedf7297c5543b27e309fb7a07597b1fef0d1c2be807678c		 vba-project OOXML VBA project: xl/vbaProject.bin 15360 bytes

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