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One free scan finds every outdated or missing driver and matches the right update for your exact hardware.Free scan · exact hardware matchOn February 18, 2015, a campaign described by CSO Online used emails disguised as fax reports to deliver malicious Compiled HTML Help (CHM) attachments. According to the March 9, 2015 report, Bitdefender Labs found that opening the attachment could trigger a download and execution sequence associated with CryptoWall 3.0. This is a historical account, not evidence of current campaign activity.
How the reported CHM attack worked
CSO Online relayed Bitdefender Labs’ account that recipients received emails made to look like fax reports, with a CHM file attached. CHM is a compiled help-document format that can package compressed HTML, images and JavaScript. In this reported case, accessing the file’s content initiated code that contacted an external location, downloaded an executable, saved it in the Windows temporary directory and ran it. CSO said a command prompt window appeared during the process.
The report does not establish that CHM files generally execute code when opened, or that CHM files are inherently malicious. It describes a particular malicious attachment and a particular reported sequence. The download address was redacted in the article; its quoted account showed a masked address ending in /putty.exe, so the destination cannot be verified from the published text.
What CSO reported about the campaign
CSO attributed the campaign details to Bitdefender Labs. The report said the email blast occurred on February 18, 2015 and targeted “a couple hundred users.” It described apparent spam-server locations in Vietnam, India, Australia, the United States, Romania and Spain, and recipient domains in the United States, Europe, Australia, the Netherlands, Denmark, Sweden and Slovakia. These are observations reported at the time, not independently verified geographic attribution or a measure of present-day activity.
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Bitdefender Labs characterized the technique as a “highly effective trick to automatically execute malware on a victim’s machine and encrypt its contents.” That quotation reflects the source’s description of the incident; it should not be read as a current assessment of CHM-file risk or ransomware prevalence.
Keep the reported figures in context
The “couple hundred users” figure refers to the February 18, 2015 CHM campaign, as CSO attributed it to Bitdefender Labs. The same article also mentions 72,000 files in a separate Dickinson County CryptoWall incident. Detective and IT director Jeff McCliss described that separate folder as containing “Every sort of document that you could develop in an investigation.” Neither figure is an independently verified count of the CHM campaign’s victims or impact.
CSO also recounted a separate Midlothian police ransom payment of $500 in bitcoin. That event is distinct from the CHM campaign and does not establish what its victims paid, if anything.
What this historical report can—and cannot—tell you
The report documents a specific 2015 delivery approach: a fax-themed email, a CHM attachment and a reported payload download and execution chain. It does not provide a current threat assessment, a comprehensive ransomware-defense plan or confirmation that the campaign remains active. The article mentioned keeping data copies on external drives; an offline backup can preserve a recovery copy, but this historical recommendation is not a complete or current security guide.
CSO also mentioned a tool called Cryptowall Immunizer. The report does not establish whether that tool is currently available, maintained or supported, so it should not be treated as a present-day recommendation.
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This account is based on CSO Online’s report, published March 9, 2015, which attributed the campaign’s technical details and scope to Bitdefender Labs. The underlying Bitdefender pages were not retrievable for this account, so those details remain claims as relayed by CSO.
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