Office (OOXML) / .XLSM malware analysis — malicious · d82c809d73585e67

MALICIOUS

Office (OOXML) / .XLSM

438.0 KB Created: 2021-07-28 10:37:27 UTC Authoring application: Microsoft Excel 12.0000

MD5: a29dcccadc623feb00357e426cfa3fee SHA-1: b3ebefd871e5c94718897d80b61ab09e2fa5088d SHA-256: d82c809d73585e67d134798aad150bec8fd431af3ad70545c416518b974f1f58

148 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1059.003 Windows Command Shell

The sample is an XLSM file containing a Workbook_Open macro, which is a common technique for executing malicious code upon opening. The macro constructs a path for a Run key entry, "HKCU\Software\Microsoft\Windows\CurrentVersion\Run\IAccessible2Proxy", and then uses CreateObject to execute a command. This command appears to download and execute a second-stage payload, as indicated by the concatenation of strings to form the executable path and the subsequent execution. The use of Environ() and Cells() suggests obfuscation to hide the true nature of the executed command.

Heuristics 5

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
Environ() call (env variable access) low OLE_VBA_ENVIRON

Environ() call (env variable access)

Extracted artifacts 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`macros.bas` `182deceeb51b35c7dc67acd5d041b6746a975f7b869553d9c457ba9121533621`	vba-macro	oletools.olevba.extract_macros (decoded VBA source from OOXML)	1146 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` `13ec60b8b1e3b7e4ad87b3d8cad84ac956e44adbc2ccf6e1b14bec42640aa62d`	vba-project	OOXML VBA project: xl/vbaProject.bin	9216 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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