Your phone receives calls that exhibit at least two of the following symptoms:

  • Display random caller ID numbers (especially 100 or 1000), weird names, or nothing.
  • Dead air (and possibly continuing to ring) when answered.
  • Device rings endlessly without going to voicemail.


Applies To

Desk phones



Ghost calls, or SIPVicious attacks, are port scans done on SIP ports for SIP-enabled devices like VoIP phones. An outside source is scanning SIP ports looking for active devices that can then be used to perform scam calls (such as fraudulent IRS calls). When the port is scanned and a device is detected, a group of packets is sent to the device to verify it is active and responding. During this process you will see the phone ring as if someone were calling.



Increase NAT Security on the Network

  1. Increase NAT security on the router or managed switch.*
  2. If a device has been configured to prevent SIPVicious attacks already, and the issue is persisting, the NAT is beginning to fail on the router. The device will need to be replaced.
Note on Netgear Nighthawk Series Routers: On all Netgear firmware versions, setting NAT to Secure causes phones to be assigned to duplicate UDP ports. This will cause connectivity issues, misrouting, and call drops. To avoid this, NAT must be set to Open. However, a Polycom phone using port 5060 may be affected with ghost calls. To fix this, a forward port rule should be set for port 5060 to an unused IP within the DHCP range. Secured NAT can be left on if there is only one phone on the LAN.

Apply a Port Forwarding Rule to the Network

In addition to increasing NAT security, you can also configure a port forward rule for SIP ports 5060 and 5061 for the TCP/UDP Protocol, forcing these packet groups to an unused IP address, which will essentially drop the ghost call.

If a router receiving ghost calls is missing the Port Forward option, it will need to be replaced (Belkin routers typically do not have port forwarding available). Modem-router combo units (e.g., AT&T units) do not allow port forwarding to deflect this traffic. These devices should be placed into bridge mode or IP Passthrough and a stand-alone router implemented


To configure a port forward rule

1.You will need to access your router’s web GUI. In the router’s web GUI, locate the section that allows you to set up Port Forwarding Rules (usually WAN or Firewall)

  1. Enable the Port Forwarding Service on your router.
  2. Set up the port forwarding rules for ports 5060 and 5061 for TCP/UDP traffic. To find out how to set up a port forwarding rule on your specific router, you may be able to find the steps here. If you are unable to locate the steps for your specific router, you may need to contact the router manufacturer for instructions.

The denial-of-service flaw in BIND can be triggered by specially crafted DNS packages and is capable of knocking critical servers offline.

The latest BIND update, versions 9.9.9-P3, 9.10.4-P3, and 9.11.0rc3, patched a denial-of-service flaw (CVE-2016-2776) that could be exploited using specially crafted DNS request packets. The issue was uncovered internally by ISC and affects all servers that can receive request packets from any source, ISC said in its advisory. Affected versions include 9.0.x to 9.8.x, 9.9.0 to 9.9.9-P2, 9.9.3-S1 to 9.9.9-S3, 9.10.0 to 9.10.4-P2, and 9.11.0a1 to 9.11.0rc1.  Users are advised to update their BIND installations to the “patched release most closely related to your current version of BIND,” or versions 9.9.9-P3, 9.10.4-P3, and 9.11.0rc3. The fix is also in the BIND 9 Supported Preview edition as version 9.9.9-S5.

The Internet Systems Consortium (ISC) patched two vulnerabilities in domain name system software BIND, one of which was referred to as a “critical error condition” in the software. BIND is the most commonly deployed DNS server on the internet, translating domain names into IP addresses so that users can access applications and remote servers without having to track IP addresses. BIND is the de facto standard on Linux and other Unix-based machines; a vulnerability in the software affects a large number of servers and applications.

The latest BIND update, versions 9.9.9-P3, 9.10.4-P3, and 9.11.0rc3, patched a denial-of-service flaw (CVE-2016-2776) that could be exploited using specially crafted DNS request packets. The issue was uncovered internally by ISC and affects all servers that can receive request packets from any source, ISC said in its advisory.

“Testing by ISC has uncovered a critical error condition which can occur when a nameserver is constructing a response,” said the ISC, which has been maintaining BIND since 2000.

The issue is tied to a defect in the rendering of messages into packets when the nameserver is constructing a response. If the vulnerability is exploited via specially crafted requests, it could trigger an assertion failure in buffer.c while constructing a response to a specific type of a query. The exploit would succeed “even if the apparent source address isn’t allowed to make queries (i.e. doesn’t match ‘allow-query’.”)

The issue was marked high-severity with a 7.8 score on the Common Vulnerability Scoring System because it can be exploited remotely. Red Hat’s advisory says the attack doesn’t require any authentication, additional privileges, or user interaction to successfully exploit the flaw, so the issue is particularly dangerous.

It’s easy to downplay the severity of a denial-of-service flaw in a security advisory, especially when compared against privilege escalation or remote code execution. However, because BIND is central to implementing the DNS protocol on the internet, a vulnerability that could be exploited to knock systems offline would have a wide-reaching impact. A specially crafted query that could crash the name server daemon isn’t simply an inconvenience or a minor setback. It could bring portions of the internet to its knees.

ISC has not seen any evidence indicating attackers were aware of or had already exploited the vulnerability, but cautioned that all servers that can receive request packets from any source should be updated. ISC has patched the faults in its distribution, and various Linux distributions, such as Red Hat, are already shipping fixes for their own BIND implementations.

The so-called “man-in-the-cloud” attack is said to be a common flaw in most cloud-based file synchronization services.


Hackers don’t even need your password anymore to get access to your cloud data.

Newly published research, released at the Black Hat conference in Las Vegas on Wednesday by security firm Imperva, shows how a “man-in-the-cloud” attack can grab cloud-based files — as well as infecting users with malware — without users even noticing.

The attack differs from traditional man-in-the-middle attacks, which rely on tapping data in transit between two servers or users, because it exploits a vulnerability in the design of many file synchronization offerings, including Google, Box, Microsoft, and Dropbox services.

This is not just an issue for consumers, but also businesses, which increasingly use cloud-based services to share sensitive customer and corporate data.

The report by Imperva, which has a research unit as well as having a commercial stake in the security space, said in some cases “recovery of the account from this type of compromise is not always feasible.”

The attack works by grabbing the password token, a small file that sits on a user’s devices for convenience (which saves the user from entering their password each time). When the token is obtained, either through a phishing attack or a drive-by exploit, it can be used to fool a new machine into thinking the attacker is the account’s owner. From there, the attacker can access and steal files, and even add malware or ransomware (which is on the rise) to the victim’s cloud folder, which can be used for further attacks.

Making matters worse, account owners are almost powerless. Because the tokens are tied to the user’s device, changing the account password would not lock out the attacker.