A month ago, I wrote a brief, half-humorous post about stopping a SIP attack. However, the unfunny truth is I have collected enough evidence documenting an ongoing, large-scale SIP attack campaign coming from ONLINE SAS (AS12876) more commonly known as “online.net.” They are also known as “Poney Telecom” and “Scaleway” in other references.
In the last few months, I’ve logged over 8,000 SIP attacks from IP addresses residing in AS12876’s network. The SIP attacks came from 401 unique IP addresses, documented here. An additional 6,000 non-SIP attacks were logged for grand total over 14,000, detailed here.
This led me to send countless abuse reports via Online.net’s Abuse Report Form. Their response was always a message saying here’s a “comment left by our customer” and that the request, was “now closed.”
Some common responses received were similar to this one:
this seems that our server has an issue or it has been hacked, I am waiting for my account to be unblocked to check server or reinstall it
Other comments were received from what appeared to be resellers:
I am really sorry for this issue, I have forward this abuse email to my client and warning him that if he do not stop this, I will turn off server
So please accept my apologize Sir
Some appeared to come from the “Scaleway Team” directly:
No answer from customer, account has been suspended by the Scaleway Team.
Unfortunately due to the sheer volume of the attacks coming from 401 unique IP addresses, I couldn’t continue using their abuse form which only allows reporting a single IP only each time.
Instead I contacted Online.net’s abuse team directly. I provided logs of the numerous attacks from hundreds of devices on their network. I did not hear back from them. Communication was only done on a per-IP basis through their abuse form.
I decided to dig a little deeper into the attacks themselves. To do this, I completed a packet capture on a tiny sample of the incoming SIP attacks.
The capture showed the attacks being performed by a device running SIPVicious.
So what is SIPVicious? Back in March 2014, Cisco issued a Security Activity Bulletin detailing SIPVicious and how it can be used:
SIPVicious is a Session Initiation Protocol (SIP) auditing tool that has been observed to be used in increasing reconnaissance attacks against IP and VoIP phones and PBX systems.
SIPVicious is used as an auditing tool for scanning phone systems by performing INVITE scans silently. However, attackers could use this feature to perform INVITE scans with a call command to determine weak passwords to connect to a particular phone host on the PBX telephony network. Access to such hosts could allow attackers to make free phone calls through a successful connection.
The tool could also be used to scan the IP or VoIP telephony network. Due to a flaw in the processing of SIP messages by the telephony device firmware, an attacker could use any number or any SIP address in the INVITE message to scan random networks to determine availability of live hosts. The attacker could initiate an INVITE session and determine a successful detection by receiving a phone ring as a response. This detection could allow the attacker to conduct further attacks such as host spoofing to make phone calls using the detected IP phone identity.
Threatpost reported SIPVicious attacks much earlier in 2011, stating that:
Though its name suggests otherwise, the Sipvicious program is a mainstream auditing tool for VoIP systems. The tool is intended to aid administrators in evaluating the security of their SIP-based servers and devices.
Rick Moy, the founder of NSS Labs, said the latest attacks seem designed to create a base from which attackers can make VoIP calls from the victim’s phone or VoIP infrastructure. Those calls might be used to rack up charges on premium rate numbers controlled by the attackers, or as part of voice phishing (vishing) scams that target unwitting consumers.
Moy said the attack shows that even “good tools’ can be used for malicious purposes.
Attacks on VoIP infrastructure are becoming more common and are often traced back to underlying vulnerabilities in VoIP infrastructure. To date, there have been some arrests. In December, authorities in Romania disrupted a criminal group that was accused of hacking VoIP servers and using them to place bogus calls to premium numbers.
I compared the IP addresses that I logged SIP attacks from with the total number of AbuseIPDB reports, shown in the chart below. There were over 6,800 AbuseIPDB reports for those 401 unique IP addresses, however there wasn’t much correlation with the 8,000 SIP attacks I logged, especially for the highest volume offenders.
Due to this, I highlighted everything above the 95th percentile in red, above the 75th percentile in yellow, and everything below in green for each column.
Next I charted unique IPs on the default SIP port only (UDP/TCP 5060) and grouped by ASN. This was because I had way too much data, so I had to exclude non-default port SIP attacks.
It’s clear most of the SIP attacks on the internet originate from AS12876’s network.
Do you see any SIP traffic from AS12876’s ranges in your logs? Are your VoIP servers properly secured?