Office (OOXML) / .XLSX malware analysis — malicious · 813ab70488289f7a

MALICIOUS

Office (OOXML) / .XLSX

16.9 KB Created: 2021-08-31 05:41:34 UTC Authoring application: Microsoft Excel 15.0300

MD5: 4e5dfd7f0fb64d8df60c6b3491d9fd82 SHA-1: c4a0369167ace521f1406435e23097a72966d209 SHA-256: 813ab70488289f7a5625d12e8398bbc4167a146e6c0b01ffd601cd2d8fae1c5d

260 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1059.003 Windows Command Shell T1204.002 Malicious File T1071.001 Web Protocols

The sample is an Excel file containing a Workbook_Open macro, which is a common technique for initial execution. The macro utilizes WScript.Shell and CreateObject to run obfuscated VBA code. This code appears to be constructing a string that likely represents a URL or command for downloading and executing a second-stage payload. The high and critical heuristic firings related to VBA execution and shell calls support this assessment.

Heuristics 6

Shell() call in VBA critical OLE_VBA_SHELL

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

WScript.Shell usage
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

Extracted artifacts 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`macros.bas` `3cada7213a42a0af36c57ddbe149aad2ba178cdf8c8abda987fd40478d542c52`	vba-macro	oletools.olevba.extract_macros (decoded VBA source from OOXML)	5746 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 shell/COM execution token(s). Carved artifact contains 7 long base64-like blob(s). Carved macro source contains an auto-exec entry point and execution/download terms.
`vbaProject_00.bin` `34b01a5b0ea07d44c60443e0e9529c1f8e526c03d23f438e3daa9b01a2a0c09a`	vba-project	OOXML VBA project: xl/vbaProject.bin	22528 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 shell/COM execution token(s). Carved artifact contains 7 long base64-like blob(s). Carved macro source contains an auto-exec entry point and execution/download terms.

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