Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 0a74d959ed393796…

MALICIOUS

RTF / .DOC

1.70 MB First seen: 2023-06-13
MD5: 755a62e73156b62f4b69a3c8db832ef5 SHA-1: 6bdd4545ad2d66e7a4a077a790773915bb17676a SHA-256: 0a74d959ed39379673bbdf37179e52dc2fb46f5de0209c1a461301a478a26027
222 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File

The RTF document contains an OLE object with decoded Equation Editor payload, strongly indicating exploitation of CVE-2017-11882. The presence of a PE file within the OLE object suggests the document's primary purpose is to download and execute a secondary malicious payload. The excessive hex data and OLE object data further support the payload delivery mechanism.

Heuristics 6

  • Equation Editor OLE1 native payload — CVE-2017-11882 related critical CVE related CVE_2017_11882_RELATED
    RTF decodes to an OLE1 Equation.3 embedded object whose native data is large and payload-like, and \objupdate requests automatic activation. This is the delivery shape used by Equation Editor RCE documents such as CVE-2017-11882/CVE-2018-0802, but the malformed MTEF record needed for exact attribution was not recovered.
  • Decoded Equation Editor payload + PE critical RTF_EQUATION_EDITOR
    RTF decodes to an Equation Editor ProgID adjacent to OLE activation and the same decoded object stream contains embedded PE bytes. This matches the Equation Editor exploit surface used by CVE-2017-11882 / CVE-2018-0802 documents, while requiring payload evidence to avoid flagging benign Equation references.
  • \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 ~1782KB of hex-encoded data inside \objdata sections — may hide a payload
  • OLE object data medium RTF_OBJDATA
    RTF contains 1 \objdata section(s) — embedded OLE objects
  • Suspicious extracted artifact info 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 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off0000008d.bin
4b55eeeb2979330535a6d59534147dc34bad3e77f6237b7b23b43c671792d8c1
rtf-objdata-decoded RTF \objdata at offset 0x8D 891070 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact entropy is 7.99, consistent with packed or encrypted content.