Introduction
Beginning on approximately May 18th, 2010 we received an email complaint relating to abuse from an IP address belonging to a network that I monitor. Early on, the FBI was directly involved in the case, so it has been treated with high regard. The compromised IP address belongs to a subnet range used for VPN access available to limited users. The account was disabled per standard procedure, but abuse continued. Further investigation suggested the hacker was of Romanian origin and has been using the network to send text message oriented spam since at least May 2010. The hacker continued to abuse the network for an extended period despite having disabled at 10-15 accounts and blocking several network blocks.
The Case
This compromise set represents an interesting case study for several reasons. First, the attacker maintained persistent access for several months. This access continued despite a well trained defensive team and a relatively unsophisticated attacker. Second, despite being familiar with SPAM and even having received numerous unsolicited text messages I was relatively unaware of text message spam as business. This attacker was very regimented and deployed numerous text messaging spam techniques and I assume generated reasonable profits. Finally, we spent time investigating this attacker and resulted in pictures of the likely attacker or at least of someone who likely is closely associated with the attacker – despite this information and the involvement of the FBI the attacker is little threatened.
Initial Reporting
The initial indicator for this compromise set was an email from a website that provides text messaging services. We have concerns regarding the overall legitimacy of the business given their primary revenue model appears to be a referral network and sending mass text messages. However, the website owner contacted us because a stolen credit card was used in purchasing their services from an IP address belonging to a network that I monitor.

We initially determined the account was compromised and disabled the user. Unfortunately, the problem resurfaced.

Given that this was a second known incident and that the FBI was involved we decided to dig more into this compromise to ensure the problem was solved and that other instances of the same issue were not continuing undiscovered.
When we examined the logs we again saw that the two incidents were linked by IP address. Upon closer investigation we also discovered the hostname appeared to be the same.

As the incidents were almost certainly linked, we decided to continue our analysis to ensure the problem did not continue to resurface.
What we’re seeing
The attacker is primarily sending text message oriented spam (see next few screenshots).





The attacker is using numerous tools to send SPAM. The spam is generally related to Voice and Text messaging services. Email to SMS gateways are spammed. Likewise SIP, Skype, and Yahoo Voice also appear to be abused. We suspect the attacker generates profit by driving telephone calls or text messages as indicated in the SPAM. The attacker is very regimented; generally logging in week days around 3pm EST (approximately 10 pm in Bucharest and sending SPAM throughout the night.
Other Activity
In the next screenshot we see the attacker accessing a US based system via FTP. While it may be possible our attacker has legitimate reason to access to this system, it is probably safer to assume this system (69.147.83.173 – an ip owned by Yahoo) is being attacked as well. This likely significantly increases the legal exposure given that an organizational IP appears to likely be compromising or attempting to compromise a remote web server.

Who is doing this?
Next we attempt to identify the attacker by following the various logs and traffic history. We have already observed that all IP addresses appear to originate in Romania. But it is conceivable that the attacker is merely pivoting from another system or compromised account. But let’s start with the IP address:

Next we look at traffic originating from the compromised vpn account. We see an automated weather beacon query MSN weather for a Romanian area.

Next, we see the user using a Romanian Google portal with a browser set to use the Romanian Character set.

We also see Skype querying a Romanian variant. The combination of a Romanian IP address, Romanian Language settings, a Romanian weather beacon, Romanian Google, and Romanian Skype gives us high confidence that the attacker is in-fact Romanian.
We continue to closely monitor the situation. We disable numerous accounts but continue to observe compromised accounts by IP and by hostname. On July 11th, the attacker makes a signifigant mistake by logging into facebook. As shown below this exposes both a facebook user ID and a yahoo email address.

Again seeing the hostname, the Romanian language settings, and the activity being in the right time frame, etc we are confident this is our attacker.
First using the email address we examine the Yahoo profile , which claims to be a 25 year old woman named Ana from Schenectady, New York.

Next we take the Facebook cookie and examined the facebook page to again find a user named Ana.

Logging into facebook we find that Ana is from Bacau, Romania.

A close up picture:

And she might be single….

As you can see from above, she appears to have clicked on a Match.com link.
Analysis of the Attacker
With a strong degree of confidence we believe the attacker is the Romanian woman. This is supported by the IP addresses of the attack, browser settings, weather beacons, and the Facebook page. We know the attacker logged in as the Facebook user “Ana Maria”. This fact does not necessarily indicate that the Facebook user is the attacker, but the attacker certainly had access to a system with the Facebook credentials for that user. That system is the same system using compromised user accounts and sending text spam for several months. Additionally the user is the Facebook profile is in the expected geographic area. Therefore it seems likely the Facebook user is the attacker or a close associate.
Mitigations to date
We made numerous efforts to block this user. We have performed the following remediation activities:
- Blocked SSL VPN connections from a specified IP range
- Created an ACL to block a specified IP range
- Disabled approximately 15 accounts
- Throttled login attempts on the SSL VPN
Despite these mitigations the attacker was able to maintain access using simple side-steps. She cycled through numerous accounts. When we blocked her IP address she switched to a different range. When we blocked that range, she used another VPN account to log into our VPN.
Summary
We have learned several lessons from this on-going case. Foremost is our inability to directly mitigate ongoing attacks. We are extremely limited in the mechanisms we can utilize to prevent determined attackers. This attacker did NOT use sophisticated tools or techniques but has successfully utilized our network despite our efforts to prevent unauthorized use for an extended period. We knew exactly what the attacker was doing, who she was, and had several additional strategies to block her. However, organizational difficulties slowed this process. A key lessoned learned is that we must develop internal communication processes with other groups to ensure that our detection and understanding of an attack can be translated into effective mitigations. Additionally, as someone who has spent serious time performing penetration tests and writing custom tools, I would have hoped to have fared better against this attacker given that I presume to know her business fairly well. Alas, defense is much harder.













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