Office (OLE) / .XLSX malware analysis — malicious · fdbad5805a56896b

MALICIOUS

Office (OLE) / .XLSX

77.0 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel First seen: 2022-05-24

MD5: 4b2bfbc9686cfbca97c9459bc09dc7b4 SHA-1: 1bf8264fa2b7f8a14204dccb48070619602866d5 SHA-256: fdbad5805a56896ba119cb50636ca0532f583847b3c93216f7768057acfe65e0

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1566.001 Spearphishing Attachment

The file contains Excel 4.0 macros, specifically an Auto_Open macro, which is a known technique for executing malicious code upon opening the document. The heuristics indicate the use of dangerous formula APIs like RUN. The extracted URLs are likely used to download and execute a second-stage payload. The presence of an Auto_Open macro strongly suggests a spearphishing attachment attack vector.

Heuristics 3

Excel 4.0 Auto_Open defined name critical OLE_XLM_AUTOOPEN_DEFINEDNAME

oletools recovered an Auto_Open / Auto_Close entry from an Excel 4.0 macro sheet. The raw BIFF name can be tokenized or partially opaque to byte-string checks, but the recovered macro listing confirms the workbook has an XLM auto-execution entry.
XLM Auto_Open with dangerous formula APIs critical OLE_XLM_DANGEROUS_FN

Excel 4.0 macro sheet contains an Auto_Open / Auto_Close entry and dangerous XLM formula APIs that can invoke programs, write files, or transfer control without VBA.
Excel 4.0 (XLM) macro sheet present medium OLE_XLM_AUTOOPEN

Workbook contains an Excel 4.0 macro sheet sub-stream — XLM is rarely seen in modern legitimate workbooks and was a major Office malware vector during 2020-2022.

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`xlm_macros.txt` `2ca0966e93dacad101ceb18f4d58731b5432892fe851526f2fda59486181312c`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	7325 bytes

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