Office (OOXML) / .XLSX malware analysis — malicious · b7153cc8f00e1f39

MALICIOUS

Office (OOXML) / .XLSX

15.9 KB Created: 2021-03-05 00:14:51 UTC Authoring application: Microsoft Excel 16.0300

MD5: ae7b06e131f2d42d049257fc25bb5af5 SHA-1: a32e070c3dc01e7c1fe14a9e0d723e2dfe47d67b SHA-256: b7153cc8f00e1f39c16da557acb8a43f57eed55a371674e995a8ac808e047ab4

220 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1059.003 Windows Command Shell

This XLSX file contains a Workbook_Open macro, a common technique for initial execution. The macro utilizes the Shell() function, with its arguments obfuscated via character-shifting functions (Mid, Asc, Chr), to execute a command. This indicates a downloader or initial execution stage designed to evade basic detection.

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
Suspicious extracted artifact high EXTRACTED_FILE_STATIC_TRIAGE

One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.
VBA project inside OOXML medium OOXML_VBA

Document contains vbaProject.bin — VBA macros present

Extracted artifacts 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`macros.bas` `2000cdd9d34a054ad03c396e9fd7ac8b9fde59b06f99c1fe6919aff3a9093906`	vba-macro	oletools.olevba.extract_macros (decoded VBA source from OOXML)	20360 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved macro source contains an auto-exec entry point and execution/download terms.
`vbaProject_00.bin` `7c6447cc0dd01651b7832726a1dbeaf479d8c7b37d9270b3635de9dc6018b671`	vba-project	OOXML VBA project: xl/vbaProject.bin	28160 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved macro source contains an auto-exec entry point and execution/download terms.

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