RTF malware analysis — malicious · c13194fcb5c94bce

MALICIOUS

RTF

1.17 MB First seen: 2019-04-18

MD5: dc92a7e5895d651e9d22935bbb2108fa SHA-1: f95c6a4357634fb070bea7b2eca6a2be3cfe01f3 SHA-256: c13194fcb5c94bce4efd55718a31d8eaa5fe737189c60673304c6d5db913b016

300 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The sample is an RTF file that contains OLE object data, including a PE header in hex-encoded data, indicating a packed executable. Heuristics confirm the exploitation of CVE-2017-8570, which is known to drop SCT scripts. The ClamAV detection as Rtf.Dropper.Agent-9965975-1 further supports its malicious nature as a dropper. The primary IOC is the file's SHA256 hash.

Heuristics 7

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.
ClamAV: Rtf.Dropper.Agent-9965975-1 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Rtf.Dropper.Agent-9965975-1
PE header (with DOS stub) in hex data critical RTF_MZ_HEX

Hex-encoded PE (MZ + DOS stub) found inside RTF — likely an embedded executable payload
\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 ~1229KB of hex-encoded data inside \objdata sections — may hide a payload
OLE object data medium RTF_OBJDATA

RTF contains 6 \objdata section(s) — embedded OLE objects
Suspicious extracted artifact medium 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 6

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`objdata_00_off00008676.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x8676	885 bytes
SHA-256: `eeabec211f2ccdc2d7c9de123e145457e6ea1837722e08b7b8d755219cd5056e`
`objdata_01_off00008d93.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x8D93	211 bytes
SHA-256: `0c03bfbfff1371e32e268860ac8c62ea75e47913714d44cf5717067983b909db`
`objdata_02_off00008f6b.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x8F6B	482 bytes
SHA-256: `8f35162cb7523f92e9f44d62d12eded23d00d10857cb163693e107bc76bbe0d8`
`objdata_03_off00009363.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x9363	850 bytes
SHA-256: `f4d52089bdd4e315fef23608700d3284f76fb6b468ae29aa8a1c54a5ef0a4a01`
`objdata_04_off00009a6e.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x9A6E	2633 bytes
SHA-256: `fe11c27d916ab897eb94064e9631d8a29c847a6db39259bef31578da8d19fdf5`
`objdata_05_off0000af48.bin`	rtf-objdata-decoded	RTF \objdata at offset 0xAF48	592588 bytes
SHA-256: `bb7490949956dd598a290ce5c8ffe3f175643f346001590d38c5b15825dd1ac3`
Detection ClamAV: No threats found Obfuscation or payload: likely Static shellcode analysis found candidate code region(s). Indicators: heap spray 0x07, SC_STR_GETPROCADDRESS Static shellcode analysis recovered API/import strings: kernel32.dll, KERNEL32.DLL, LoadLibraryA, GetProcAddress, VirtualAlloc

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