Office (OLE) / .XLS malware analysis — malicious · e6e5b5116db79b0d

MALICIOUS

Office (OLE) / .XLS

411.5 KB Created: 2021-10-19 13:23:47 Authoring application: Microsoft Excel

MD5: 782ec47e6f2d74e4e571526b717c965e SHA-1: 71c72099069c46f451b8917f7b5a3ff0b872893c SHA-256: e6e5b5116db79b0d86a588cb9b0259986eaa6afefd58cb97139a439787caedb9

368 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1105 Ingress Tool Transfer T1204.002 Malicious File

This XLS file contains VBA macros that are automatically executed upon opening, as indicated by the Workbook_Open heuristic. The script utilizes ShellExecuteA and URLDownloadToFile APIs, suggesting an intent to download and execute a second-stage payload. The `Decrypt("fyf/qjou")` call likely reconstructs a URL or filename, which is then used for the download. The ClamAV detection and multiple critical heuristics confirm its malicious nature.

Heuristics 9

Reference to URLDownloadToFile API critical SC_STR_URLDOWNLOAD

Reference to URLDownloadToFile API
URLDownloadToFile in VBA critical OLE_VBA_DOWNLOAD

URLDownloadToFile in VBA
ClamAV: Xls.Malware.Valyria-10028013-0 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Xls.Malware.Valyria-10028013-0
Reference to ShellExecute API high SC_STR_SHELLEXEC

Reference to ShellExecute API
Workbook_Open macro high OLE_VBA_WBOPEN

Workbook_Open macro
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.
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 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` `8c9831347683dc63b857d150b77e8a2dd0ad5179ee605d57b3ec6befae9f75da`	vba-macro	oletools.olevba.extract_macros (decoded VBA source)	14902 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 shell/COM execution token(s). Carved artifact contains 12 long base64-like blob(s). Carved macro source contains an auto-exec entry point and execution/download terms.

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