RTF malware analysis — malicious · 42ca876acb5dba3d

MALICIOUS

RTF

487.7 KB First seen: 2021-04-01

MD5: 700d3abc4844c597c830aee8a72b25e0 SHA-1: be5abbe3630b6dca0a56f6e9876968d31fdb5ef1 SHA-256: 42ca876acb5dba3dfe8b22d5f4def04f04bfffb8a6fc5521defddc117d4c78f5

320 Risk Score

Heuristics 8

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.
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.
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

Extracted artifacts 4

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`objdata_00_off000007f8.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x7F8	141051 bytes
SHA-256: `063ee6a917f1fb4ef165bbc879be18c1fc08575c6ac69c8a824596332caf969e`
Detection ClamAV: No threats found Obfuscation or payload: likely Static shellcode analysis recovered command string(s): WScript.Shell"")")
`objdata_01_off00004106.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x4106	141025 bytes
SHA-256: `71f63872cd5c7b4bda3b531e4ddda0c95523539d438a3e42a979427559e4e1b8`
Detection ClamAV: No threats found Obfuscation or payload: likely Static shellcode analysis recovered command string(s): WScript.Shell"")")
`objdata_02_off0004bb7b.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x4BB7B	2632 bytes
SHA-256: `3cd3b7d42e5855c90d6d11c54ef2670ed8970441480cc23f7d39ef08fa1c935b`
`objdata_03_off0004d11e.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x4D11E	12297 bytes
SHA-256: `e8d4fe950caed6dcfde26f4b616825bbe11b93458425974b7d075167f675abf7`

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