RTF malware analysis — malicious · 40e52901b3698180

MALICIOUS

RTF

402.4 KB First seen: 2021-01-23

MD5: a11a29f2ba373dbf518553e505c1137d SHA-1: 844427c386b00e5e551f9399e90faf6de26633a4 SHA-256: 40e52901b36981803ed70fdb38a78537aa03658ecd8b17c9797f92b7b135d955

340 Risk Score

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.
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
Macro/content-enable lure medium SE_ENABLE_LURE

Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings

Extracted artifacts 4

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`objdata_00_off00000bca.bin`	rtf-objdata-decoded	RTF \objdata at offset 0xBCA	98591 bytes
SHA-256: `cd4208711238859787f98ab023453f8989ab9e19a8cf0ce78939178f71de4a4a`
Detection ClamAV: No threats found Obfuscation or payload: likely Static shellcode analysis recovered command string(s): Wscript.Shell"" ) ")
`objdata_01_off000044d8.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x44D8	98565 bytes
SHA-256: `7fa79d35fbc68bb0f359c25d5e64d5f01a76d8a7411c6db8c741715ac1e43551`
Detection ClamAV: No threats found Obfuscation or payload: likely Static shellcode analysis recovered command string(s): Wscript.Shell"" ) ")
`objdata_02_off0003664f.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x3664F	2632 bytes
SHA-256: `9898055bd0f8f4ea4768ba3581db647387d886eacf12252bf69adb6e4fce9c36`
`objdata_03_off00037bf2.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x37BF2	12297 bytes
SHA-256: `e8d4fe950caed6dcfde26f4b616825bbe11b93458425974b7d075167f675abf7`

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