RTF malware analysis — malicious · c8f304435bb5a3f1

MALICIOUS

RTF

560.4 KB First seen: 2019-04-17

MD5: ea0dc4b4b77276e999375ae33c28d560 SHA-1: fcb0bd823af48056542cee6039e44e9e5efa88e1 SHA-256: c8f304435bb5a3f1dd340c295dbeb59620ab682244dde08566ddd11b93f5f04b

182 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF file contains multiple OLE objects and ".objupdate" directives, indicating it is designed to exploit vulnerabilities. Specifically, the "CVE_2017_8570" heuristic firing confirms the use of a Composite Moniker to drop an SCT script, which is a known technique for executing arbitrary code. The embedded OLE object data, particularly at offset 0xB5D2, is the likely source of this exploit.

Heuristics 6

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.
\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.
OLE object data medium RTF_OBJDATA

RTF contains 7 \objdata section(s) — embedded OLE objects
Embedded OLE object medium RTF_OBJEMB

RTF contains \objemb — embedded OLE object
Suspicious extracted artifact info 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.

Extracted artifacts 7

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`objdata_00_off00000025.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x25	229 bytes
SHA-256: `bdf6de0a64b3411ca5229f989a8704bb9f2ac8eac0d3b0c83ab62136585dd012`
`objdata_01_off0000021e.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x21E	260839 bytes
SHA-256: `6d8f08faaf4d54fafe2b47afad5ec8b4417a264f1dd6c536a930f38748e10c78`
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 7.91, consistent with packed or encrypted content.
`objdata_02_off0008937d.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x8937D	1123 bytes
SHA-256: `263c6a332f8bed14e4d9417cab11f921ef8d301d5b5d655b5a43179ea58c7434`
`objdata_03_off00089c7c.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x89C7C	636 bytes
SHA-256: `beeb549ebc57e264e8e77fa6b4cfd820bf95bef53865f2e41c70d776aef38923`
`objdata_04_off0008a1ac.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x8A1AC	404 bytes
SHA-256: `392cac683130eb6402c5b549f0e7d1653f531eebb9a09e8b26c73d30cf6c8b98`
`objdata_05_off0008a510.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x8A510	937 bytes
SHA-256: `e21955e19ee5e9c33caa29d20574aba20d6cc02b855734ac20377ad351eddf3c`
`objdata_06_off0008ace0.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x8ACE0	2633 bytes
SHA-256: `ce081fd28fe7177ff803b92dfff0940839fdacbc316318ce15cbf8889540f4f0`

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