Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 241367cd4f08afe3…

MALICIOUS

RTF / .DOC

1.05 MB First seen: 2023-09-13
MD5: 290fce33014ad508c6a7e7cf17c2e991 SHA-1: beb0df0e8d7344d428ec63b7f820be08c50ad76a SHA-256: 241367cd4f08afe3402847a7ecbc5c83f54d1c3c3693d00ea6a103d7ed597a9b
222 Risk Score

Malware Insights

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

The RTF document contains an embedded OLE object that leverages the Equation Editor vulnerability (CVE-2017-11882). This vulnerability is known to be used for arbitrary code execution, allowing the embedded payload to be decoded and run. The high entropy and size of the decoded object suggest it contains a packed or encrypted executable.

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 ~1104KB 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_off00000087.bin
626dac9d5e212f77409bff8459492940e8876edcf78fa691097a5af761cd9162
rtf-objdata-decoded RTF \objdata at offset 0x87 552251 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact entropy is 7.99, consistent with packed or encrypted content.