ABC: Al Qaeda Videos May Be Doctored
Neal Krawetz a security consultant and researcher using a program he
wrote can print out the quantization tables in a JPEG file and
determine the last tool that created the image, the make and model of
the camera and if the image is original or the
version of Photoshop that was used to alter and re-save the image.
used an example from 2006 al- Qaeda video of Ayman al-Zawahiri, a
senior member of the terrorist organization. After conducting his error
analysis Krawetz was able to determine that
al-Zawahiri's image was superimposed in front of the background -- and
was most likely videotaped in front of a black sheet. (Modified
versions will indicate a different error level than the original
Further, Krawetz conducted analysis on a another 2006 video of Azzam the American.
Analysis also shows that the books in Azzam have a different color range than
the rest of the image, indicating that they came from an alternate
source. The books could be added to a picture to send a message in code to al Qaeda operatives.
One computer expert, however, has conducted extensive image analysis on many of the videos and concluded that in many cases the tapes were likely doctored to give a false impression of the speaker’s location.
By looking at the error levels of the
different elements in the still frames, or JPEGs, he can tell which
elements are older and which are newer. In other words, he can tell
which areas of the video were modified more recently.
For example, in one video of Zawahri
released in July of last year, he appears to be seated in a news studio
complete with a backdrop of images of the World Trade Center attacks
and hijacker Mohammed Atta.