Got FreeBSD? Get busy on the patch, because a problem with its TCP ordering has emerged, with both denial-of-service and data leakage as possible effects.
The issue exists in how the popular Unix-like operating system handles TCP packets received out-of-order. Packets are held in a reassembly queue until they can be re-ordered and re-assembled. However, as the advisory states:
“FreeBSD may add a reassemble queue entry on the stack into the segment list when the reassembly queue reaches its limit. The memory from the stack is undefined after the function returns. Subsequent iterations of the reassembly function will attempt to access this entry.”
Crafted packets can cause a kernel crash, the advisory states, but worse: “because the undefined on stack memory may be overwritten by other kernel threads, while extremely difficult, it may be possible for an attacker to construct a carefully crafted attack to obtain portion of kernel memory via a connected socket”.
Ty Miller, CEO of Threat Intelligence, said in an e-mail the operating system is the basis of kit from a lot of well-known names, including: OSX, PlayStation, some Panasonic TVs; and security gear from Blue Coat, Checkpoint, IronPort, Juniper, McAfee and Sophos.
The difficulty of creating an exploit means this is far less likely to cause data leak before patches start becoming available. One issue, however, is very similar to Heartbleed: because FreeBSD is behind the scenes in non-obvious places, a lot of systems may never get patched.
While sysadmins will have charge of IT systems, almost no one except the very savvy home user patches consumer kit.
It should be noted that users will probably see denial-of-service rather than data leak as the most immediate potential impact. “Because of the complexity associated with the exploitation process, it is more likely to trigger the target system to crash,” Miller's e-mail noted.
Patch instructions are given at the FreeBSD advisory. ®