Office (OLE) / .XLS malware analysis — malicious · 7ae27df148d5128a

MALICIOUS

Office (OLE) / .XLS

38.0 KB Created: 2022-04-11 01:05:12 Authoring application: Microsoft Excel First seen: 2022-04-11

MD5: c70ce0e30b4a2c5b1798519baa3c7d47 SHA-1: 5359ce2148a33fd1866f7b7a98329317a2f3fd50 SHA-256: 7ae27df148d5128a1216716155077aeaf3ca8f6d4764ed043afc47fb55055e1f

368 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1105 Ingress Tool Transfer T1059 Command and Scripting Interpreter

The sample is a macro-enabled Excel file containing a Workbook_Open macro that executes obfuscated VBA code. This code constructs a URL to download a second-stage executable, identified as 'transfer.sh/yljuH/0001KLC2022.exe', and saves it to the user's temporary directory as '%TEMP%\klc.exe'. The script then attempts to execute the downloaded file, indicating a downloader or droppper functionality.

Heuristics 9

VBA downloads and writes a file to disk critical OLE_VBA_HTTP_DROP_EXEC

VBA reads an HTTP response body and writes it to disk (ADODB.Stream SaveToFile). Combined with the auto-exec/Shell paths this is a download-drop dropper even when the COM ProgIDs are built dynamically to evade keyword scanning.
Obfuscated auto-exec VBA loader critical OLE_VBA_OBFUSCATED_AUTOEXEC_LOADER

Auto-exec VBA reconstructs strings with a heavy custom decoder (numeric char-array, repeated hex-string decode, or junk-token Replace removal) and feeds them to a COM-instantiation or execution sink. This obfuscated-loader shape keeps CreateObject/Shell/URL indicators out of the macro source.
ClamAV: Xls.Malware.Sload-7135989-0 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Xls.Malware.Sload-7135989-0
Workbook_Open macro high OLE_VBA_WBOPEN

Workbook_Open macro
CreateObject call high OLE_VBA_CREATEOBJ

CreateObject call
GetObject call high OLE_VBA_GETOBJ

GetObject call
VBA p-code auto-exec with execution tokens high OLE_VBA_PCODE_AUTOEXEC_EXEC

Compiled VBA/cache stream contains an auto-execution token together with shell/download/object-execution tokens. This catches p-code-only or source-extraction-failure macro documents where visible source is unavailable.
VBA macros detected medium OLE_VBA_MACROS

Document contains VBA macro code
Environ() call (env variable access) low OLE_VBA_ENVIRON

Environ() call (env variable access)

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`macros.bas` `d131f6964dea8b0d5ba71c9e08eeb9f73c70bb1996bb9d5b962090e16a392faf`	vba-macro	oletools.olevba.extract_macros (decoded VBA source)	4363 bytes

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