Malicious RTF — malware analysis report

Static analysis result for SHA-256 35d7a707a408998e…

MALICIOUS

RTF

8.3 KB First seen: 2019-05-16
MD5: 2a8ea0694001cfe82a41008a6a83fcd8 SHA-1: 8e3be105b82fc71e8f57501b6fa35fa08be69064 SHA-256: 35d7a707a408998e803b537931a24f09c0df8ac288073e2a6c7e00884d4efbb5
240 Risk Score

Malware Insights

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

The sample is an RTF document containing an embedded OLE object that exploits the CVE-2017-11882 vulnerability in Microsoft Equation Editor. This exploit is known to allow for arbitrary code execution, typically used to download and run a second-stage payload. The presence of the Equation Editor CLSID and the specific FONT record overflow signature strongly indicate this exploit is being leveraged.

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_off00000033.bin rtf-objdata-decoded RTF \objdata at offset 0x33 4132 bytes
SHA-256: 46e95ff23df866070eb898baa2122539ad1c6e99b40bad44ab0dc9a59dca2d0b