RTF malware analysis — malicious · a5ce22e19a13b0ad

MALICIOUS

RTF

1.32 MB First seen: 2019-05-16

MD5: 356198232be81a9e887eab01ad14d037 SHA-1: 06ead723b291a58715f5f08d3bfaa819030f5b36 SHA-256: a5ce22e19a13b0ad26be00a9c005bbf8526d29a792045bfa6df15be0f2d7473f

380 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution

The RTF file contains multiple OLE objects, with specific heuristics indicating the use of Composite Moniker and objupdate to force OLE activation, consistent with CVE-2017-8570. This vulnerability is known to drop and execute SCT scripts. The presence of large amounts of hex-encoded data within the OLE objects suggests a hidden payload. ClamAV detections further confirm the malicious nature of the file and its extracted artifacts.

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.
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.Packed.Nanocore-10018911-0 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Win.Packed.Nanocore-10018911-0
\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 ~1345KB of hex-encoded data inside \objdata sections — may hide a payload
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 5 \objdata section(s) — embedded OLE objects
Embedded OLE object medium RTF_OBJEMB

RTF contains \objemb — embedded OLE object

Extracted artifacts 5

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`objdata_00_off00000025.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x25	672568 bytes
SHA-256: `033b922f2b42bd3d15b230e80b1cb7f6f949d26671ced26504952fda4161af12`
Detection ClamAV: Win.Packed.Nanocore-10018911-0 Obfuscation or payload: likely Carved artifact entropy is 7.98, consistent with packed or encrypted content.
`objdata_01_off0014dea1.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x14DEA1	1056 bytes
SHA-256: `38e0a590df7eaa9868af736886281809be3c0fe6a6a6ea4e0327baa813cb5642`
`objdata_02_off0014e717.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x14E717	429 bytes
SHA-256: `c861ab3ab7d28ef7b028a69afbbfc89c1f5c98f0be9f15b26f0565b7d5605703`
`objdata_03_off0014eaa5.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x14EAA5	1351 bytes
SHA-256: `fbfe6031f946bf25c25f9783662a0516de4f34007dcfe7ff53f2b540dbc1df3f`
Detection ClamAV: No threats found Obfuscation or payload: likely Static shellcode analysis recovered command string(s): cscript //nologo %vbs%
`objdata_04_off0014f59a.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x14F59A	2633 bytes
SHA-256: `798252dd8256ec7c0f3355fdbdacc1463a701b0cfdd8d20a5bf75796675244ff`

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