Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 bdb9aed749025c83…

MALICIOUS

RTF / .DOC

1.56 MB First seen: 2023-02-17
MD5: c6ac34ba9fdbc22842d4711c30ccf641 SHA-1: 0e5bf480394419dbce956a1795e481b4b91c6b27 SHA-256: bdb9aed749025c83407a143cc9492bc96e13122c4e096154e79fd59720e8363c
222 Risk Score

Malware Insights

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

The RTF document contains a decoded Equation Editor payload, strongly indicating exploitation of CVE-2017-11882. The presence of OLE object data and excessive hex-encoded data further suggests the embedding of a malicious executable. The file likely serves as a dropper for a secondary payload, leveraging the vulnerability to bypass initial security measures.

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 ~1630KB 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_off00000079.bin
b2c331362150b68ce502369bf35b4d3e79dc926eb8c053824ada5ad0d41394d4
rtf-objdata-decoded RTF \objdata at offset 0x79 815685 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact entropy is 7.99, consistent with packed or encrypted content.