Malicious RTF — malware analysis report

Static analysis result for SHA-256 bc8adccb74f5ae8f…

MALICIOUS

RTF

686.2 KB First seen: 2018-10-07
MD5: ebfe41b0a49cba062c3a682be28a5096 SHA-1: b413af08ca4a91fa0be9703217f474f3ccddecff SHA-256: bc8adccb74f5ae8f5c0d3f4cf5c8b08dcf0c8018bfafa37bd2afafc09e9be6d6
442 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution

The RTF file contains multiple indicators of malicious activity, including OLE object data and a critical firing for CVE-2017-8570, which is known to drop SCT scripts. An embedded URL, http://test1.ru/newbuild/t.php?thread=0&stats=send, is present and likely serves as a download source for a secondary payload. ClamAV detections further confirm the presence of packed malware, specifically GandCrab.

Heuristics 10

  • 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.Gandcrab-6552923-4 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Win.Packed.Gandcrab-6552923-4
  • 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.
  • INCLUDETEXT/INCLUDEPICTURE remote URL high RTF_INCLUDE_REMOTE
    RTF document uses INCLUDETEXT or INCLUDEPICTURE with an http:// URL — Word can fetch the remote content on open depending on Office version and external-content settings, enabling remote template injection, NTLM capture via redirects, or payload delivery
  • 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 6 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object
  • 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://test1.ru/newbuild/t.php?thread=0&stats=send In RTF body
    • http://schemas.microsoft.com/office/word/2003/wordml}}\paperw11906\paperh16838\margl1701\margr850\margt1134\margb1134\gutter0\ltrsectIn RTF body

Extracted artifacts 6

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off0001c79f.bin rtf-objdata-decoded RTF \objdata at offset 0x1C79F 36660 bytes
SHA-256: 8617b90243ea60aa3c6efa067896940b775354ead12b582742a31988bf0a9983
objdata_01_off0002e63f.bin rtf-objdata-decoded RTF \objdata at offset 0x2E63F 355 bytes
SHA-256: 3195b1bb51f48678bbe4dca3a7cd77a2ecfaf683d76f3b6382c1ffd5124a7220
objdata_02_off0002e93d.bin rtf-objdata-decoded RTF \objdata at offset 0x2E93D 250051 bytes
SHA-256: e978f5d2680fd61a356b72b85844bcbc138c362fdab371e232b38d59d0476b52
Detection
ClamAV: Win.Packer.Crypter-6539596-1
Obfuscation or payload: likely
Static shellcode analysis found candidate code region(s). Indicators: SC_PEB_ACCESS, SC_STR_VIRTUALALLOC, SC_STR_GETPROCADDRESS Static shellcode analysis recovered API/import strings: VirtualAlloc, GetProcAddress, ExitProcess Carved artifact entropy is 7.44, consistent with packed or encrypted content.
objdata_03_off000a8afb.bin rtf-objdata-decoded RTF \objdata at offset 0xA8AFB 2336 bytes
SHA-256: 1e718c98482888205ce4801225fa04eb564a3f0c52e4fd67224788723ca94f24
objdata_04_off000a9d73.bin rtf-objdata-decoded RTF \objdata at offset 0xA9D73 718 bytes
SHA-256: 47c9f25d1fd95c77751f00e655e09f132ca19d6899d7b72208f6d7610e321458
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Static shellcode analysis recovered command string(s): WScript.Shell")
objdata_05_off000aa351.bin rtf-objdata-decoded RTF \objdata at offset 0xAA351 2633 bytes
SHA-256: 1b11531569c98284e74e6ae4c14275a0ab013edb5d6151ea140c1c38c40ac41e

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