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

Static analysis result for SHA-256 c036e8dc1366569d…

MALICIOUS

Office (OLE) / .XLS

345.5 KB
MD5: ef3daeab1598c56f4e4324a23457887b SHA-1: caac968378bf73059ba955926b263aae724fe79f SHA-256: c036e8dc1366569d7d3c54ce9f71bee82d76046f397c8ca5fdd67123b28c575c
280 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1140 Deobfuscate/Decode Files or Information T1566.002 Spearphishing Attachment

The sample exhibits characteristics of a downloader, indicated by the presence of an embedded SWF file and the use of XOR-encoded strings, likely to obfuscate malicious content. References to WinExec, LoadLibrary, and GetProcAddress APIs further suggest dynamic code execution. The embedded Flash object and obfuscated strings point towards an attempt to download and execute a second-stage payload from one of the unknown reputation URLs.

Heuristics 7

  • XOR-encoded strings (key 0x03) critical SC_XOR_ENCODED
    Found 8 Windows library/API name(s) XOR-encoded with single-byte key 0x03: 'VirtualAlloc', 'VirtualAlloc', 'VirtualAllocEx', 'VirtualProtect', 'VirtualProtectEx', 'CreateProcessA', 'WriteProcessMemory', 'ReadProcessMemory'
  • Embedded Adobe Flash (SWF) in OLE document critical OFFICE_EMBEDDED_SWF
    Document contains an embedded Adobe Flash (SWF) object. Vulnerabilities such as CVE-2018-4878 and CVE-2018-15982 involved Flash objects embedded in Office files. Adobe Flash has been end-of-life since December 2020.
  • Reference to WinExec API high SC_STR_WINEXEC
    Reference to WinExec API
  • Reference to LoadLibrary API high SC_STR_LOADLIBRARY
    Reference to LoadLibrary API
  • Reference to GetProcAddress API high SC_STR_GETPROCADDRESS
    Reference to GetProcAddress API
  • OLE document has large unaccounted-for region high OLE_SLACK_ANOMALY
    OLE file is 353,792 bytes but its declared streams total only 56,346 bytes — 297,446 bytes (84%) live in unallocated sector slack. This is the canonical hiding place for pre-macro-era Office exploit payloads (XOR-encoded shellcode reached via a parser pointer-corruption bug in the document structure).
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL http://www.ad-artists.de
    • http://www.wormfans.com/
    • http://www.lao13.com/
    • http://www.wormfans.com/cgi/front/subscribe/
    • http://www.microsoft.com
    • https://www.verisign.com/rpa
    • http://ocsp.verisign.com/ocsp/status0
    • https://www.verisign.com/rpa0
    • http://crl.microsoft.com/pki/crl/products/CodeSignPCA.crl0

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