Office (OOXML) / .XLSX malware analysis — malicious · 1b7821a2e0c24aeb

MALICIOUS

Office (OOXML) / .XLSX

410.7 KB Created: 2020-04-17 18:58:39 UTC Authoring application: Microsoft Excel 16.0300

MD5: fed0c95a5a525ffa57a495d9ee631f66 SHA-1: e22fd76642733b209a380f0a9dbe8920bc560c58 SHA-256: 1b7821a2e0c24aeb38ae3a90b5c85c410fdc2e08c43e4964b1cca670d5543897

440 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1059.003 Windows Command Shell T1204.002 Malicious File T1105 Ingress Tool Transfer

The file contains a Workbook_Open macro that executes obfuscated VBA code. This code utilizes WScript.Shell and character-shifting techniques to decode and execute a command, likely downloading and running a secondary payload. ClamAV detections indicate this is a known downloader/dropper family.

Heuristics 10

Shell() call in VBA critical OLE_VBA_SHELL

Shell() call in VBA
WScript.Shell usage critical OLE_VBA_WSCRIPT

WScript.Shell usage
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.
ClamAV: Xls.Downloader.DridexGreen09213-9890103-0 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Xls.Downloader.DridexGreen09213-9890103-0
ClamAV detection on extracted artifact critical EXTRACTED_FILE_CLAMAV

ClamAV flagged at least one file extracted from inside this sample. Even when the wrapping document carries no AV detection of its own, a hit on the carved artifact is a strong indicator the sample is a delivery vehicle.
Workbook_Open macro high OLE_VBA_WBOPEN

Workbook_Open macro
CreateObject call high OLE_VBA_CREATEOBJ

CreateObject call
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` `32ee6deb29e3fd864b04917d05cfe85d7169c71e2edeac295cdf4d0ac3d3e74f`	vba-macro	oletools.olevba.extract_macros (decoded VBA source from OOXML)	2177 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 shell/COM execution token(s). Carved macro source contains an auto-exec entry point and execution/download terms.
`vbaProject_00.bin` `233daea2301a4d1296fae456b6b6efa5d88da81aa5ac41a6987550fbda1f2f7a`	vba-project	OOXML VBA project: xl/vbaProject.bin	13824 bytes
Detection ClamAV: Xls.Dropper.Agent-7672717-0 Obfuscation or payload: likely Carved artifact contains 1 shell/COM execution token(s). Carved macro source contains an auto-exec entry point and execution/download terms.

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