New Denial-of-Service Attack Tool Uses Relay Chat

Remember the distributed denial-of-service attack tools, like Tribal Flood Network and Trin00, that last February were used in mass attacks on Web sites owned by EBay, E*Trade, CNN and Yahoo? Security experts this week say an even more dangerous tool, called Trinity, has just been discovered.

Trinity is a Linux-based distributed denial-of-service attack tool that a hacker can use to launch a massive IP flood against a victim's targeted computer, much the way its predecessors TFN and Trin00 do.

The Trinity software agent must first be secretly installed on a hacked Linux server; after that, the agent can be remotely controlled to launch a network flood en masse, in tandem with other compromised machines.

Trinity is a better tool for the attack, because it can be controlled through either a standard Internet Relay Chat (IRC) channel or AOL's chat, ICQ.

"With the older distributed denial-of-service attack tools, the hacker has to keep a list of all the machines he broke into, while with Trinity, they all report to you, and all these Trinity agents appear in the same chat room," says Chris Rouland, director of the Internet Security Systems "swat" team called the X-Force. "From a hacker's perspective, that's great."

The chat feature in the new Trinity distributed denial-of-service attack tool makes it easier for the hacker to launch an attack and helps the hacker prevent his real identity from being uncovered, since hackers typically change their IP address for use in a chat channel.

Rouland says at least 400 Linux computers - with IP addresses indicating they may be located mainly in the U.S., Romania, and Australia - have already been compromised by Trinity. That means they could be used to launch a distributed denial-of-service attack on a victim's computer.

To make use of the attack tool, a hacker first has to secretly install the Trinity agent code on a Linux server. Once done, the compromised server is forced to join an IRC channel called "#b3eblebr0x" using a special password, Rouland says.

The "#b3eblebr0x" chat channel (which seems to use AT&T as its network service) is a kind of underworld IRC server - accessed through secret password only - run by hackers to use distributed denial-of-service. There appear to be other IRC channels like this as well, Rouland notes.

The Linux "zombie" machines were compromised when hackers broke into them by exploiting a default setting for the network file system through an RFC buffer overflow, Rouland explains. "If you trace it back, it will give you root shell [access]," he says.

ISS first learned of the Trinity distributed denial-of-service attack tool when it was recently brought to the attention of the Forum of Incident Response Teams - an umbrella organization for security notification groups such as CERT - by an educational institution which found some campus computers infected by it. The educational institution has not been named. After reverse engineering the Trinity code, ISS saw several references to the word "Trinity" in it and decided to call it that.

Network administrators with Linux servers can take a number of steps to prevent their servers from becoming hosts for the Trinity attack software. They can use scanning tools - such as the ISS Internet Scanner - to scan for it. And they can block IRC traffic on ports 6665, 6666 and 6667. ISS recommends blocking Internet access to chat channels. "Chat is a conduit for distribution of malicious code," Rouland says. "It's a way to distribute Trojans, and, in addition, users who don't know how to hide their IP address will reveal it during chat. On the Internet, chat is risky business."

Rouland points out that ISS Tuesday discovered a chat room called "IP Victims" on Yahoo that is being used for the exchange of IP addresses of machines compromised by the Trojan horse Back Orifice and an older distributed denial-of-service attack tool called Sub Seven.

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