Office (OOXML) / .XLSX malware analysis — malicious · 3c40af3b0d480922

MALICIOUS

Office (OOXML) / .XLSX

13.1 KB Created: 2020-04-02 14:48:53 UTC Authoring application: Microsoft Excel 16.0300

MD5: d2f8ee9828a8c81fab29241e293344f6 SHA-1: 9cada1e8bb0a8ae341dfe721878c7115c1469aa5 SHA-256: 3c40af3b0d480922a1888dcc95765aa30fa4033dcb08284b4cf0b2e70c6a994c

220 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1059.001 PowerShell

This XLSX file contains a Workbook_Open macro, a common technique for initial execution. The macro employs character-shifting functions (Mid, Asc, Chr) to decode a command that is subsequently executed via the Shell() function. This indicates the file is designed to download and execute a second-stage payload. The specific command decoded is not fully reconstructible from the provided evidence, but the presence of these elements strongly suggests a malicious intent.

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` `2e75ecc4a28715d7797e2c4fbca1112a6de30b775b0fbc7f703c456057bec88f`	vba-macro	oletools.olevba.extract_macros (decoded VBA source from OOXML)	2568 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` `096e754eacb98a92fc8d22809cf0a07f858f606939be46599e7c230dac4f17e2`	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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