Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 f72c86685e499993…

MALICIOUS

RTF / .DOC

696.6 KB Created: 2021-04-08 20:37:00 First seen: 2021-04-25
MD5: 81dd489e42f29b03815d2533e8e89b94 SHA-1: a379c3031448a4ecc9e42816912f5328cd8ca467 SHA-256: f72c86685e49999377ce344c9fa547abb9c7fa979f68bbc0e9a7bfe28aee309d
402 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The sample is an RTF document that leverages multiple OLE object vulnerabilities, including CVE-2017-8570 and CVE-2017-0199/CVE-2017-8759. These vulnerabilities allow the RTF file to automatically download and execute a secondary payload. The presence of 'objupdate' and 'Composite Moniker' firings strongly indicates an exploit chain designed to bypass security measures and achieve remote code execution.

Heuristics 11

  • 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.
  • CVE-2017-0199 / CVE-2017-8759 (OLE2Link auto-activated remote loader) critical CVE related RTF_OLE2LINK_REMOTE_MONIKER_LOADER
    RTF embeds an OLE2Link object that is force-activated with \objupdate (no user interaction on open) and fetches a remote second stage — through an INCLUDETEXT/INCLUDEPICTURE field or the OLE object's own moniker. This is the OLE2Link auto-update attack path shared by CVE-2017-0199 (server returns an HTA/scriptlet) and CVE-2017-8759 (server returns a SOAP WSDL the .NET parser compiles). Office processes the fetched response through the same code path; the specific CVE depends on the now-unreachable server content type.
  • 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.
  • CVE-2026-21514 — Word/OLE security bypass in RTF high CVE likely CVE_2026_21514
    RTF contains a hidden \svb hex package with DrsE2oDoc and downRevStg drawing compatibility parts. This matches an observed CVE-2026-21514 exploitation shape that manipulates Word's internal document structure and trust decisions.
  • Automatically linked OLE object high RTF_OBJAUTLINK
    RTF contains \objautlink — an automatically linked OLE object surface that can be updated or activated when Word opens the document.
  • \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.
  • \objupdate activation with payload hidden outside \objdata high RTF_OBJUPDATE_LOOSE_HEX_PAYLOAD
    RTF declares an OLE object with \objupdate (forces automatic activation when the document opens) but has no \objdata destination; the object payload is instead dumped as a large loose hex-encoded region in the document body. This split hides the payload from \objdata-scoped parsers while Word still instantiates the object. Structurally exclusive to weaponised documents.
  • 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.
  • OLE object data medium RTF_OBJDATA
    RTF contains 4 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object
  • 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
🗂 Part of campaign: shared payload 3cd3b7d42e 51 samples

Extracted artifacts 5

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off000451cc.bin rtf-objdata-decoded RTF \objdata at offset 0x451CC 103003 bytes
SHA-256: a06772f0f6eaaca38295f0c3f01d992b752386e2332bcffa2e740f3153e113cd
objdata_01_off0004b97b.bin rtf-objdata-decoded RTF \objdata at offset 0x4B97B 102976 bytes
SHA-256: 2d7644b77e3907777bf83f2e8c0743a9e740a98079c136abd203de5b2b7a873d
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Static shellcode analysis recovered command string(s): WScript.Shell"")")
objdata_02_off0007feca.bin rtf-objdata-decoded RTF \objdata at offset 0x7FECA 2632 bytes
SHA-256: 3cd3b7d42e5855c90d6d11c54ef2670ed8970441480cc23f7d39ef08fa1c935b
objdata_03_off0008146d.bin rtf-objdata-decoded RTF \objdata at offset 0x8146D 12297 bytes
SHA-256: e8d4fe950caed6dcfde26f4b616825bbe11b93458425974b7d075167f675abf7
rtf_svb_0000c98b.zip rtf-svb-package RTF \svb hex-decoded ZIP at offset 0xC98B 2929 bytes
SHA-256: b968a2cec16a2eccd3aa86666a8f79959f25062cf3ec8dcae40e416083f7cd8a