Office (OLE) / .XLS malware analysis — malicious · 8290655a81cf1cee

MALICIOUS

Office (OLE) / .XLS

71.0 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel First seen: 2022-06-07

MD5: 3a0a7d86decf124ddeec9c075d3e92b2 SHA-1: 4cebc9f1da4ef841f5da39ba5393414f8633c7ba SHA-256: 8290655a81cf1cee72d85aee9889729d9d2691ee506e4bd590896b6b5cc5ab08

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1566.001 Spearphishing Attachment

The critical heuristics indicate the presence of Excel 4.0 macros with an Auto_Open entry, which is a common technique for executing malicious code within older Excel versions. The macro sheet contains concatenated URLs that are likely used to download and execute a second-stage payload. The use of Auto_Open suggests this file was likely delivered as a spearphishing attachment.

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` `b4f0a647cf6176132ebc9ecde0dbe63bae14d0fc3c1b3805926fc56fef0b0f6a`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	7650 bytes

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