The Inspire magazine, produced by al-Qaeda's Yemeni affiliate - al-Qaeda in the Arabian Peninsula, which regularly includes how-to instructions for followers to carry out terrorist attacks in the West - has received significant scrutiny in recent weeks.
Investigators believe that Boston bomber Tamerlan Tsarnaev accessed Inspire magazine, and the material had instructions on bomb-making, a law enforcement official told CNN.
According to analysts, the explosive devices the Boston bombers built had striking similarities to a bomb recipe in the first issue of the magazine, "How to build a bomb in your Mom's kitchen", that has been downloaded by militants in multiple Islamist terrorist plots.
Josh Lefkowitz, a senior partner at Flashpoint, said they detected the new posting Tuesday evening on the administrator account of the top-tier, password-protected forum Al Fidaa, a website regularly used to disseminate propaganda from al-Qaeda and its affiliates.
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All the links led to the same corrupted PDF file, and within minutes, the posting had been deleted from the web forum completely.
The purported new issue titled, "How did it come to this?" was dated "Spring 2013" and contained no mention of the Boston attack on its cover page.
According to Flashpoint's analysis, the metadata on the new purported Inspire magazine shows it was last modified on April 8, a week before the Boston bombings.
Metadata is electronic data on the creation and modification of files, but it can itself be corrupted.
The cover page included a content caption "Open Source Jihad," which in past issues has been a section featuring do-it-yourself terrorism advice.
Lefkowitz said there are several possible explanations for the scrambled file, ranging from a hoax perpetrated by a sophisticated hacker to intervention from intelligence agencies.