Office (OOXML) / .XLSX malware analysis — malicious · 2c7f398eaa2ddcf1

MALICIOUS

Office (OOXML) / .XLSX

237.9 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-03-11

MD5: b65b73f33b85d678a43db4058716eda5 SHA-1: b1f3bc22cd9fb39d57a13bddcf8bb3cf04ffb763 SHA-256: 2c7f398eaa2ddcf13272d8880627fd4f799e3136be2075eb228ec06184709994

180 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The sample is an OOXML file containing multiple Excel 4.0 macro sheets, flagged by heuristics as malicious. The embedded macro sheets are heavily obfuscated and truncated, preventing a detailed analysis of their specific actions. However, the presence of these macro sheets strongly suggests an attempt to execute arbitrary code upon opening the document.

Heuristics 3

Excel 4.0 macro sheet (3 sheet(s)) critical OOXML_XLM_MACROSHEET

Spreadsheet contains an Excel 4.0 (XLM) macro sheet — XLM was a major Office malware vector during 2020-2022 and evaded many VBA-focused controls before Microsoft tightened XLM defaults. Even legitimate XLM use is rare in modern workbooks. The macro sheet is stored as XLSB/BIFF12 binary content, which many XML-only OOXML scanners miss.
XLSB international XLM macro sheet hidden in .xlsx critical OOXML_XLSB_INTL_MACROSHEET_IN_XLSX

OOXML package is named .xlsx but contains XLSB workbook parts and an international Excel 4.0 macro sheet. This hides XLM macro execution from scanners that trust the extension or only inspect XML worksheet parts. The technique is macro execution, not a document-parser CVE.
ClamAV: Multios.Malware.Agent-10043485-0 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Multios.Malware.Agent-10043485-0

Extracted artifacts 3

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`xlm_sheet_00.bin` `e544b7ab0da06c170490d3c79fb93c6f6f400c122451cf0debcb64018e387492`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet1.bin	2504 bytes
`xlm_sheet_01.bin` `294fba96533e16b8e32fcc670b890c44fe9dfc759e5d84743c74026ba7bd4a20`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	428 bytes
`xlm_sheet_02.bin` `f0daf3cbff097906d4170f35f5f5c2394e9b70d2a487782035c708617ae7b9ec`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet2.bin	428 bytes

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