Office (OLE) / .XLS malware analysis — malicious · 1a457bbc6c53f297

MALICIOUS

Office (OLE) / .XLS

31.0 KB Created: 2021-01-20 12:57:58 Authoring application: Microsoft Excel

MD5: 8892f7bf793c729f1367f8fd0b89371d SHA-1: b491215ec214dcd8d8a37273d186d26da784ea17 SHA-256: 1a457bbc6c53f2977963f9a5a10d6d0ef97bdc96c9dc3826aa41743376e854b6

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1566.001 Spearphishing Attachment

The sample is an Excel 4.0 macro-enabled spreadsheet. Heuristics indicate the presence of an Auto_Open macro, which is a common technique for executing malicious code upon opening the document. The 'RUN' function is identified as a dangerous API call within the macro, suggesting it is used to launch an external process. The exact payload or URL is not directly visible in the provided macro listing, but the intent is to execute a secondary stage.

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` `f26f8ce47bf745bb17277e2f8126ab86b873c1eeb6840dcdd35e5c5e21563c5b`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	3540 bytes

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