Office (OOXML) / .XLSX malware analysis — malicious · db41aeaea5cbc6bf

MALICIOUS

Office (OOXML) / .XLSX

13.1 KB Created: 2020-04-04 15:46:20 UTC Authoring application: Microsoft Excel 16.0300

MD5: 86d4ede2dd447fcde284c6f112187bf5 SHA-1: ba5ffa5523c9c77230e2195c1100d375a187ea93 SHA-256: db41aeaea5cbc6bf9efc53685b28bf2495f12227d006bb34f8733c1e5bfff7cd

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 that utilizes the Shell() function. The command executed by Shell() is obfuscated using character-shifting functions (Asc, Mid, Chr) but ultimately decodes to a command that likely downloads and executes a second-stage payload. The presence of a Workbook_Open macro and the use of Shell() are strong indicators of malicious intent, typical of macro-based malware droppers.

Heuristics 6

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
Embedded URL info EMBEDDED_URL

One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
URL http://schemas.openxmlformats.org/spreadsheetml/2006/main
- http://schemas.openxmlformats.org/officeDocument/2006/relationships
- http://schemas.openxmlformats.org/markup-compatibility/2006
- http://schemas.microsoft.com/office/spreadsheetml/2009/9/ac
- http://schemas.microsoft.com/office/spreadsheetml/2014/revision
- http://schemas.microsoft.com/office/spreadsheetml/2015/revision2
- http://schemas.microsoft.com/office/spreadsheetml/2016/revision3

Extracted artifacts 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`macros.bas` `bb28310338518ec6b833852e7960a5014268c9a440909d2fc1581ed8e846ce2d`	vba-macro	oletools.olevba.extract_macros (decoded VBA source from OOXML)	2556 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` `cecb5761879e49bfda5f48a364b9f9eb3a94a8689599068b7d618037a5645ab4`	vba-project	OOXML VBA project: xl/vbaProject.bin	13824 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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