Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 172e6a908015dd95…

MALICIOUS

RTF / .DOC

1.59 MB First seen: 2023-02-07
MD5: 34abb90224f8b4fd057e8fa8f5a3eb0b SHA-1: 8199cd6f8fba690059d7b8cac0627deba569d78b SHA-256: 172e6a908015dd956c606d2efa00ee8fe6ed43cd9000631dad346227e0ef5450
222 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File T1059.003 Windows Command Shell

The RTF document contains an embedded OLE object that leverages the Equation Editor vulnerability (CVE-2017-11882) to execute a payload. The high entropy and size of the decoded object suggest it contains a packed or encrypted executable. The presence of ".objdata" and ".objupdate" sections further indicates the exploitation of OLE object vulnerabilities within the RTF structure.

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 ~1671KB 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
0cd9a3a7848e1fbdbb760d73f2084f3c045b518f8ee60766e8544ae13a8a8816
rtf-objdata-decoded RTF \objdata at offset 0x79 835901 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact entropy is 7.99, consistent with packed or encrypted content.