Malicious RTF — malware analysis report

Static analysis result for SHA-256 b1f48c6f5cc82045…

MALICIOUS

RTF

1.29 MB First seen: 2020-02-04
MD5: 4ccdf78c1f68aeb57921e88c1f980bcf SHA-1: e253f54a7a1bf0bf1f2944cee091fff98c7312b8 SHA-256: b1f48c6f5cc82045073607fd6152ac2b7e9fd8f0af75963bfe82f3718758d555
402 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution

The RTF file contains OLE object data with a Composite Moniker, indicating exploitation of CVE-2017-8570. This vulnerability is known to drop SCT scripts, which are then executed. The presence of a PE header within the hex data further suggests the embedded object is a Windows executable payload. The extracted artifact objdata_05_off0002a4ef.bin likely contains this payload.

Heuristics 9

  • Composite Moniker — CVE-2017-8570 (drops SCT script) critical CVE related CVE_2017_8570
    RTF \objdata decodes to OLE data containing the Composite Moniker — CVE-2017-8570 (drops SCT script) CLSID — the vulnerable control/moniker is embedded directly in the document's object stream, the delivery shape of this exploit. RTF objects auto-render when Word opens the file.
  • Composite Moniker in RTF OLE object high CVE related RTF_COMPOSITE_MONIKER_RELATED
    RTF contains Composite Moniker CLSID in OLE object context, but no nearby scriptlet/SCT payload was confirmed. Treat as related moniker attack-surface evidence rather than proof of CVE-2017-8570 exploitation.
  • ClamAV: Win.Malware.Filerepmalware-6709941-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Win.Malware.Filerepmalware-6709941-0
  • PE header (with DOS stub) in hex data critical RTF_MZ_HEX
    Hex-encoded PE (MZ + DOS stub) found inside RTF — likely an embedded executable payload
  • \objupdate forces OLE activation high RTF_OBJUPDATE
    RTF contains \objupdate — forces automatic OLE object instantiation when the document is opened, bypassing user interaction. Almost exclusively seen in Equation Editor exploit documents.
  • Large hex data blocks in OLE object high RTF_EXCESSIVE_HEX
    RTF contains ~1349KB of hex-encoded data inside \objdata sections — may hide a payload
  • OLE object data medium RTF_OBJDATA
    RTF contains 6 \objdata section(s) — embedded OLE objects
  • Suspicious extracted artifact medium 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.
  • 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://schemas.microsoft.com/office/word/2003/wordml In RTF body

Extracted artifacts 6

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00018657.bin rtf-objdata-decoded RTF \objdata at offset 0x18657 873 bytes
SHA-256: c481ae32e55cd5aed2c08c2e2d44fffd4c3c894b98dd0aadef7fe1bcc1714b99
objdata_01_off00018d62.bin rtf-objdata-decoded RTF \objdata at offset 0x18D62 31676 bytes
SHA-256: 8e1be3feb782a829ff258a0e054e4c260ab6864e307e975e6874709ef91bf7cf
objdata_02_off00028512.bin rtf-objdata-decoded RTF \objdata at offset 0x28512 487 bytes
SHA-256: fbdc08917d7c4e786f601c1fc37cd61fc0fa1fdd4c6590c37bf66bf37ded9f73
objdata_03_off0002891c.bin rtf-objdata-decoded RTF \objdata at offset 0x2891C 833 bytes
SHA-256: a57103bc84a2998af640e20eec949b44c7cbeb12765e1e7ce6b5161436b0b531
objdata_04_off0002900f.bin rtf-objdata-decoded RTF \objdata at offset 0x2900F 2633 bytes
SHA-256: 1feb5f150bb35566d1a01fc59a357dc0ea34bc7498e0ec99bd939f6f848044b0
objdata_05_off0002a4ef.bin rtf-objdata-decoded RTF \objdata at offset 0x2A4EF 588492 bytes
SHA-256: 75e721eb59d0e02bbc287107125e01177aaf07be242abd943c7ca4673e971a99
Detection
ClamAV: Win.Malware.Filerepmalware-6709941-0
Obfuscation or payload: likely
Static shellcode analysis found candidate code region(s). Indicators: SC_MSF_REVERSE, SC_STR_VIRTUALALLOC, SC_STR_LOADLIBRARY Static shellcode analysis recovered API/import strings: LoadLibraryExA, VirtualAlloc, GetProcAddress, ExitProcess