Malicious RTF — malware analysis report

Static analysis result for SHA-256 24929c1c0b22da52…

MALICIOUS

RTF

128.3 KB First seen: 2020-02-04
MD5: 904b14d2549f6b58e4303eaa5ebb7d87 SHA-1: 53393f2165a36acc7e1ead9fd580fdfc68f03ed3 SHA-256: 24929c1c0b22da52174fea464926874801475082574d9a39135a0d81c390d212
240 Risk Score

Malware Insights

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

The sample is an RTF document that contains embedded OLE object data, specifically triggering heuristics related to Equation Editor and CVE-2017-11882. This indicates the file is designed to exploit this vulnerability for client-side execution. The presence of ".objupdate" further suggests an attempt to activate the embedded object. Given the exploit, the likely intent is to download and execute a secondary payload, making it a malicious attachment delivered via spearphishing.

Heuristics 5

  • Equation Editor CLSID critical CVE likely RTF_EQUATION_EDITOR
    Equation Editor OLE CLSID found inside an OLE object — exploited by CVE-2017-11882 / CVE-2018-0802 / CVE-2018-0798
  • CVE-2017-11882 — Equation Editor FONT record overflow critical CVE likely CVE_2017_11882
    Equation Editor MTEF contains an overlong FONT typeface field, the vulnerable copy primitive for CVE-2017-11882. This is stronger evidence than the Equation Editor CLSID alone because it identifies the malformed record that drives code execution in EQNEDT32.EXE.
  • ClamAV: Doc.Exploit.CVE_2017_11882-6934206-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Exploit.CVE_2017_11882-6934206-0
  • \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.
  • OLE object data medium RTF_OBJDATA
    RTF contains 1 \objdata section(s) — embedded OLE objects

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00001f75.bin rtf-objdata-decoded RTF \objdata at offset 0x1F75 4412 bytes
SHA-256: 001cfd80f932e0691e166b4766d67de96af86c179bb682f077643f5cff270daf