Malicious RTF — malware analysis report

Static analysis result for SHA-256 8868ff5ce2075d86…

MALICIOUS

RTF

1.50 MB First seen: 2023-08-18
MD5: dff7f0552e91826b222d16879dfda268 SHA-1: 54cdc50879ff98d660c8273b0efd7ec8105e12de SHA-256: 8868ff5ce2075d865f44441eddb2a008c5c36336f422fb5ebcf5338f59644bd6
242 Risk Score

Malware Insights

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

The RTF document contains an embedded OLE object specifically targeting the Equation Editor vulnerability (CVE-2017-11882). This vulnerability is known to be used to execute arbitrary code when the embedded object is activated. The presence of a PE file within the decoded object data strongly suggests that the exploit is used to drop and execute a secondary malicious payload.

Heuristics 7

  • 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 ~1572KB 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
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object
  • 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_off00000088.bin
970147d0672aee79b17f6f648a9fac679a5c33af0de4cbbf7dc3bfc61cf481fa
rtf-objdata-decoded RTF \objdata at offset 0x88 786426 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact entropy is 7.99, consistent with packed or encrypted content.