Malicious Office (OLE) / .XLSX — malware analysis report

Static analysis result for SHA-256 d788edf3a3dc40e7…

MALICIOUS

Office (OLE) / .XLSX

537.9 KB
MD5: db0d1611db13f668bd21be777c151654 SHA-1: 110a74cbc4988cf902d07e9063c37bb629adbf33 SHA-256: d788edf3a3dc40e7b85c1dec4cbf32211e12d6d4e641948c0e3f61ee093f2616
200 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1059 Command and Scripting Interpreter T1204.002 User Execution: Malicious File T1566.001 Phishing: Spearphishing Attachment T1204.001

The sample is an encrypted Office document containing OLE objects that trigger CVE-2018-0798 in the Equation Editor. The high entropy in the native stream suggests the presence of a shellcode payload. ClamAV detection as a downloader indicates the likely intent is to fetch and execute a second-stage payload.

Heuristics 5

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Default-encrypted OOXML embedded OLE object xl/embeddings/oleObject1.bin contains the Equation Editor CLSID, the legacy component exploited by CVE-2017-11882, CVE-2018-0802, and CVE-2018-0798.
  • CVE-2018-0798 — anomalous Equation Editor native stream high CVE likely CVE_2018_0798_EQUATION_NATIVE_ANOMALY
    Default-encrypted OOXML contains embedded Equation Editor data with anomalous native stream bytes consistent with a CVE-2018-0798-style exploit. This is treated as likely CVE evidence because the Equation object is malformed and payload-like.
  • ClamAV: Xls.Downloader.af2fa5c5d0587870-9978799-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.af2fa5c5d0587870-9978799-0
  • Default-encrypted OOXML exploit carrier layout high OOXML_ENCRYPTED_EXPLOIT_CARRIER_SHAPE
    Default-password encrypted OOXML package contains embedded OLE object parts and additional activation/decoy parts. This layout is common in malicious Excel exploit delivery and requires inspecting the decrypted package.
  • Office OOXML encrypted with default VelvetSweatshop password medium OFFICE_DEFAULT_PASSWORD_ENCRYPTED_OOXML
    OLE EncryptedPackage decrypts with Excel's built-in VelvetSweatshop password. Office opens this transparently, and malware uses it to hide OOXML exploit parts from scanners that only inspect the outer OLE container.