Malicious RTF — malware analysis report

Static analysis result for SHA-256 823fa05a348d91f6…

MALICIOUS

RTF

720.9 KB Authoring application: LibreOffice/7.1.2.2$Linux_X86_64 LibreOffice_project/8a45595d069ef5570103caea1b71cc9d82b2aae4 First seen: 2026-06-04
MD5: f28ef3e66d7a8459f8ab38f4aa56f5cf SHA-1: 35d7cf1efe99f9875fb332f3b576525c3172ae81 SHA-256: 823fa05a348d91f66ee9c38d815a79ff07b2b5757ea8a5fea4db43f017deb906
320 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution

The RTF document contains OLE objects that leverage vulnerabilities like CVE-2017-0199 or CVE-2017-8570. These vulnerabilities are known to facilitate the execution of remote code or the download of additional malicious content. The presence of 'Composite Moniker' and 'OLE2Link auto-activated remote loader' heuristics strongly indicates an exploit attempting to fetch and run a secondary 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.
  • CVE-2017-0199 / CVE-2017-8759 (OLE2Link auto-activated remote loader) critical CVE related RTF_OLE2LINK_REMOTE_MONIKER_LOADER
    RTF embeds an OLE2Link object that is force-activated with \objupdate (no user interaction on open) and fetches a remote second stage — through an INCLUDETEXT/INCLUDEPICTURE field or the OLE object's own moniker. This is the OLE2Link auto-update attack path shared by CVE-2017-0199 (server returns an HTA/scriptlet) and CVE-2017-8759 (server returns a SOAP WSDL the .NET parser compiles). Office processes the fetched response through the same code path; the specific CVE depends on the now-unreachable server content type.
  • 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.
  • Automatically linked OLE object high RTF_OBJAUTLINK
    RTF contains \objautlink — an automatically linked OLE object surface that can be updated or activated when Word opens the document.
  • \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.
  • 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 4 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object
🗂 Part of campaign: shared payload 51ef705eef 49 samples

Extracted artifacts 4

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off0000f3e9.bin rtf-objdata-decoded RTF \objdata at offset 0xF3E9 221081 bytes
SHA-256: aa4234721ed8218a533443295b758d2ef192cc235ce308dd56e8b087a3418d9a
objdata_01_off00015b98.bin rtf-objdata-decoded RTF \objdata at offset 0x15B98 221054 bytes
SHA-256: 06cac6cb386a6c3c002c08d4dce06f137a28b04af5da0ed3842b3b002eff0bd0
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Static shellcode analysis recovered command string(s): WScript.Shell"")")
objdata_02_off00086049.bin rtf-objdata-decoded RTF \objdata at offset 0x86049 2632 bytes
SHA-256: 51ef705eef602ac6eb91c2063c8f50d4e54b5e051b60429031d41133bc7df645
objdata_03_off000875ec.bin rtf-objdata-decoded RTF \objdata at offset 0x875EC 12297 bytes
SHA-256: e8d4fe950caed6dcfde26f4b616825bbe11b93458425974b7d075167f675abf7