Malicious RTF — malware analysis report

Static analysis result for SHA-256 8e13e6ebd64127ad…

MALICIOUS

RTF

6.33 MB First seen: 2019-11-20
MD5: a73757f4b743e7834a71611a06d149fb SHA-1: c43cb06301f52f10b073c49c82de5735b0d51b33 SHA-256: 8e13e6ebd64127ade5cf05f8e9cc5b20a6fb70228729e5717edb75ae0a7d4381
222 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF file contains an embedded OLE object that decodes to a PE file, strongly indicating exploitation of the CVE-2017-11882 vulnerability in Microsoft Equation Editor. This technique is commonly used to achieve arbitrary code execution on the victim's machine. The extracted artifact 'objdata_00_off0000006b.bin' is the likely payload.

Heuristics 6

  • Decoded Equation Editor payload + PE critical CVE likely 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.
  • 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.
  • \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 ~6635KB 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_off0000006b.bin rtf-objdata-decoded RTF \objdata at offset 0x6B 3317619 bytes
SHA-256: e62f631e70b8276d07a7c3ec0213b569a9f305b48ba1d62a580658370ede985e
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact entropy is 7.99, consistent with packed or encrypted content.