ImageMagick, an open source command line graphics file editor, has been retired by one of its major consumers: Yahoo. The product has been beset by flaws and bugs for several years, but this appears to have been one too many for Yahoo. Following discovery of a bleed vulnerability, Yahoo fixed it by retiring the product.
The flaw itself, discovered by researcher Chris Evans, was fixed by ImageMagick two months ago. Last week, however, he blogged about his discovery of its persistence at Yahoo. For Evans, it is symptomatic of a wider issue: vendor (ImageMagick) and consumer (in this case Yahoo) responsibility for upstream fixes.
ImageMagick (using his own fix) fixed the problem. Could or should it have done more to ensure that its consumers also applied that fix? Yahoo is (or was) a consumer. Could it or should it have done more to apply upstream fixes?
A solution, suggests Evans, is, “Probably less trivial than it sounds; both Box and Yahoo! appear to have been running old versions of ImageMagick with known vulnerabilities.”
The vulnerability, exploited by Evans on Yahoo, provided “a way to slurp other users’ private Yahoo! Mail image attachments from Yahoo servers.” It was present in the RLE (Utah Raster Toolkit Run Length Encoded) image format. An attacker, writes Evans, “could simply create an RLE image that has header flags that do not request canvas initialization, followed by an empty list of RLE protocol commands. This will result in an uninitialized canvas being used as the result of the image decode.”
In his own POC he attached an 18-byte exploit file as a Yahoo! Mail attachment, sent it to himself and clicked on the image in the received mail to launch the image preview pane. “The resulting JPEG image served to my browser,” he writes, “is based on uninitialized, or previously freed, memory content.”
He reported the problem to Yahoo, and was pleased with Yahoo’s response. It was fixed well within Yahoo’s self-imposed 90-day deadline, and, he says, the communication was excellent. Compare this to his comments on communication with Box: “communications were painful, as if they were filtered through a gaggle of PR representatives and an encumbrance of lawyers.”
The fix itself was simple and complete: Yahoo retired ImageMagick.
Despite its problems over the last few years, Yahoo has come a long way with improving its vulnerability response approach. In 2013, High-Tech Bridge (HTB) found numerous XSS flaws in Yahoo servers. “Each of the discovered vulnerabilities,” it said at the time, “allowed any @yahoo.com email account to be compromised simply by sending a specially crafted link to a logged-in Yahoo user and making him/her click on it.”
The HTB researcher was offered a $12-50 Yahoo store voucher for each of the flaws. This time, however, Evans as offered a total of $14,000 for this and a separate issue yet to be documented. When Evans suggested donating it to charity, Yahoo doubled the charitable award to $28,000.
SecurityWeek has asked Yahoo for a comment on the issue, but has not yet received a reply.