Malicious RTF — malware analysis report

Static analysis result for SHA-256 0aa6ad540cef4f7c…

MALICIOUS

RTF

1.34 MB First seen: 2020-09-15
MD5: d184d4c572e2a5293702067b875817d3 SHA-1: f06799d38bb7457f7f5623a19bffc5a5439c937a SHA-256: 0aa6ad540cef4f7c3583accdb2d103681f2ebf066928df8760f2b5668fbd58f2
300 Risk Score

Malware Insights

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

The RTF file contains embedded OLE object data, specifically identified as a decoded Equation Editor payload related to CVE-2017-11882. This exploit is known to facilitate the execution of arbitrary code. The presence of a high-entropy, shellcode candidate artifact further supports that this file is a dropper designed to execute a secondary payload.

Heuristics 7

  • 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.
  • ClamAV: Rtf.Dropper.Agent-9756463-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Rtf.Dropper.Agent-9756463-0
  • \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 ~1408KB 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 medium 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_off00000044.bin rtf-objdata-decoded RTF \objdata at offset 0x44 704060 bytes
SHA-256: c85aa8a53af0dd16e849a6f95b5386f8eb062a627bbe6ee531da9cd49209b258
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Static shellcode analysis found candidate code region(s). Indicators: SC_GETPC_CALL Carved artifact entropy is 7.99, consistent with packed or encrypted content.