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CallStranger vulnerability lets attacks bypass security systems and scan LANs:
A severe vulnerability resides in a core protocol found in almost all internet of things (IoT) devices.
The vulnerability, named CallStranger, allows attackers to hijack smart devices for distributed denial of service (DDoS) attacks, but also for attacks that bypass security solutions to reach and conduct scans on a victim's internal network -- effectively granting attackers access to areas where they normally wouldn't be able to reach.
According to a website dedicated to the CallStranger vulnerability published today, the bug impacts UPnP, which stands for Universal Plug and Play, a collection of protocols that ship on most smart devices.
Also at Ars Technica.
[...] Çadirci says that an attacker can send TCP packets to a remote device that contains a malformed callback header value in UPnP's SUBSCRIBE function.
This malformed header can be abused to take advantage of any smart device that was left connected on the internet, and which supports the UPnP protocols -- such as security cameras, DVRs, printers, routers, and others.
In a CallStranger attack, the hacker effectively targets the device's internet-facing interface, but executes the code on the device's UPnP function, which usually runs on the internally-facing ports only (inside the LAN).
[...] In addition, Çadirci also published proof-of-concept scripts that companies can use to determine if their smart equipment is vulnerable to any of the CallStranger attacks.
The CallStranger security flaw is also tracked as CVE-2020-12695. There are currently around 5.45 million UPnP-capable devices connected to the internet, making this an ideal attack surface for IoT botnets and APTs.
(Score: 2) by hendrikboom on Sunday June 14 2020, @02:38AM (1 child)
I lave a Linux box (debian/devuan) from which I removed minidlna some time ago -- uninstaled teh packages. But there are still packages around with upnp and dlna around. Removing them causes pacakes like gstreamer to get removed too, which is I gather is something various desktop applications use.
I have no idea whether these other packages actually provide the vulnerability.
What software in the usual Linux mix actually provides this vulnerability? or has it already been patched ages ago and I have little to worry about?
-- hendrik
(Score: 0) by Anonymous Coward on Sunday June 14 2020, @07:57AM
This is a two part vulnerability. If UPnP isn't enabled on your WAN, you should be fine for the first part.
As to the second part, you should check your dependency tree in order to know for sure that nothing uses them. If you are worried but don't want to parse the trees, just firewall the ports. If nothing breaks, you are golden. Otherwise, you can watch https://kb.cert.org/vuls/id/339275 [cert.org] and Debian's security page for statements on affected software. As this vulnerability is so new, it is sort of difficult to say who is and isn't vulnerable at this point. However, as the various vendors look at their software, it should become clear.