Malicious RTF — malware analysis report

Static analysis result for SHA-256 be1cdc2aa4aca6ca…

MALICIOUS

RTF

1.41 MB First seen: 2019-08-04
MD5: b1aca2dad61e3c32dce97dbab0b2f444 SHA-1: fbf7bf5243a8c6e16ca4cb92cb98262a69fce997 SHA-256: be1cdc2aa4aca6ca137a63dd3a9c26ba8d869f180cd12d4e0b0bbf0b0092eb4b
242 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF file contains multiple indicators of malicious activity, including the presence of OLE objects and a Composite Moniker, strongly suggesting exploitation of CVE-2017-8570. This vulnerability is known to drop and execute SCT scripts. The heuristic 'CVE_2017_8570' specifically points to this exploit, which facilitates client execution by dropping a script. The presence of a large, hex-encoded OLE object further supports the likelihood of a hidden payload.

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.
  • \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 ~1383KB of hex-encoded data inside \objdata sections — may hide a payload
  • 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 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.
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL http://schemas.openxmlformats.org/drawingml/2006/main In RTF body

Extracted artifacts 7

Files carved from inside the sample during analysis.

FilenameKindSourceSize
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 691939 bytes
SHA-256: 76a17409127aa16814e864f62322270fdc7cb329883c7e7a26710aa7633a946c
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Static shellcode analysis found candidate code region(s). Indicators: SC_MSF_REVERSE, SC_STR_VIRTUALALLOC, SC_STR_LOADLIBRARY Static shellcode analysis recovered API/import strings: LoadLibraryExA, VirtualAlloc, GetProcAddress, ExitProcess
objdata_02_off001572d9.bin rtf-objdata-decoded RTF \objdata at offset 0x1572D9 1123 bytes
SHA-256: 263c6a332f8bed14e4d9417cab11f921ef8d301d5b5d655b5a43179ea58c7434
objdata_03_off00157bd8.bin rtf-objdata-decoded RTF \objdata at offset 0x157BD8 31460 bytes
SHA-256: b30fc706e3044d6a9a2cfc9db1bd0f3e8acaf676ffd7c63484f5e67381ce83b4
objdata_04_off001671d8.bin rtf-objdata-decoded RTF \objdata at offset 0x1671D8 404 bytes
SHA-256: 392cac683130eb6402c5b549f0e7d1653f531eebb9a09e8b26c73d30cf6c8b98
objdata_05_off0016753c.bin rtf-objdata-decoded RTF \objdata at offset 0x16753C 937 bytes
SHA-256: e21955e19ee5e9c33caa29d20574aba20d6cc02b855734ac20377ad351eddf3c
objdata_06_off00167d0c.bin rtf-objdata-decoded RTF \objdata at offset 0x167D0C 2633 bytes
SHA-256: ce081fd28fe7177ff803b92dfff0940839fdacbc316318ce15cbf8889540f4f0

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