Malicious RTF — malware analysis report

Static analysis result for SHA-256 aedc0d055a4753e7…

MALICIOUS

RTF

1.77 MB First seen: 2021-07-07
MD5: a63cbe05aa331a4da0d95a103898f465 SHA-1: 5286293ff55ffebe777982ac093b24e95f7d4668 SHA-256: aedc0d055a4753e7b137a3d0661731e0f455d2b8f4ee959b7732beaf9e378499
220 Risk Score

Malware Insights

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

The RTF file contains embedded OLE objects, specifically triggering heuristics related to Equation Editor and CVE-2017-11882. The presence of shellcode command strings within an extracted artifact further indicates the execution of a malicious payload. The exploit likely serves as a delivery mechanism for a secondary stage, commonly seen in phishing attacks.

Heuristics 6

  • Split hex Equation Editor ProgID + OLE object critical CVE likely RTF_EQUATION_EDITOR
    RTF embeds the Equation.3 ProgID as hex bytes near OLE object activation and splits the byte stream with whitespace or an ignorable RTF group. This is an Equation Editor OLE activation surface commonly used by CVE-2017-11882 / CVE-2018-0802 exploit documents.
  • Equation Editor activation — CVE-2017-11882 related high CVE related CVE_2017_11882_ACTIVATION_RELATED
    RTF decodes to an Equation.3 ProgID and requests OLE activation with \objemb plus \objupdate. This reaches the legacy Equation Editor attack surface used by CVE-2017-11882/CVE-2018-0802 documents, but the malformed MTEF/native payload needed for stronger 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.
  • Suspicious extracted artifact high 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.
  • OLE object data medium RTF_OBJDATA
    RTF contains 2 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off000011e1.bin rtf-objdata-decoded RTF \objdata at offset 0x11E1 54073 bytes
SHA-256: 027de20c0a370f8d0b4a4034fedadb598d54bfdd079a7b8c5a8f5cdfa7b310a1
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Static shellcode analysis recovered command string(s): Wscript.ScriptFullName
objdata_01_off0002fea5.bin rtf-objdata-decoded RTF \objdata at offset 0x2FEA5 452820 bytes
SHA-256: a3c4dea994dc8ee11a4f63de30f7dfa57dd55c2b1c12c19d818507bc177d14a2