Researchers find bugs in archive file formats

They found it is possible to conceal malware within archive formats such as .rar and .zip

Researchers have found ways to hide malicious software in commonly used archival formats that went undetected until recently by most antivirus programs.

Most antivirus vendors have patched their applications in order to detect the tampered archive file formats, such as ".rar," and ".zip," said Tomislav Pericin, founder of the commercial software protection project RLPack.

Perison gave a presentation at the Black Hat security conference on Thursday with Mario Vuksan, an independent security researcher, and Brian Karney, the COO of AccessData.

The three researchers showed how it is possible to tamper with the archive formats and insert malicious code such as the Conficker worm, which is then executed on a person's computer.

Many corporations use so-called "gateway" security products that analyze file attachments to see if they're malicious. Hackers have found that compressing malicious files -- also known as "packing" -- can sometimes trip up security products, although those products are much better now at that kind of detection.

But the researchers showed that by tampering with different archival formats, it is still possible to evade those gateway products. That's dangerous, since an end user may then open an attachment that could allow a hacker to have remote access to a computer.

"The problem is the AV vendors and the archive vendors have two different solutions. If they don't work in sync, the user can extract an archive on their PC, but the AV won't be able to, and that's a problem," Pericin said.

Most end users do run antivirus software, which means that an executable such as Conficker would be detected when it runs. But the researchers found at least eight vulnerabilities in which security products didn't catch the bad files. Most of the affected vendors have deployed patches, Pericin said.

They've also found at least 30 other potential vulnerabilities in security products, but they're waiting for all vendors to roll out patches to see if those problems persist, Pericin said.

There are no intrinsic problems in the archival file formats themselves, and it will always be possible to modify those files, Pericin said.

The researchers also showed how it is possible to embed secret content within an archive file. The technique is generally known as stenography, or a way to write hidden messages known only to the sender and recipient. There are at least two software tools that can put hidden messages into ".zip" files.

Stenography "has a lot of implications," Pericin said. "If you are a terrorist, for example, and you want to hide communication, if you use encryption, the government can detect that. But if you hide stuff and no one is looking at it, you have this obscure channel of communication that works."

However, the researchers released on Thursday a free, open-source tool that can spot both malicious software and hidden content in archival formats. Called NyxEngine, it preprocesses archive formats, breaking inside and inspecting what's inside. It supports the ".zip," ".rar," ".gz" and ".cab" formats.

Tags Archivingblack hatbugsstenographymalware

Keep up with the latest tech news, reviews and previews by subscribing to the Good Gear Guide newsletter.

Jeremy Kirk

IDG News Service

Comments

Comments are now closed.

Latest News Articles

Most Popular Articles

Follow Us

GGG Evaluation Team

Kathy Cassidy

STYLISTIC Q702

First impression on unpacking the Q702 test unit was the solid feel and clean, minimalist styling.

Anthony Grifoni

STYLISTIC Q572

For work use, Microsoft Word and Excel programs pre-installed on the device are adequate for preparing short documents.

Steph Mundell

LIFEBOOK UH574

The Fujitsu LifeBook UH574 allowed for great mobility without being obnoxiously heavy or clunky. Its twelve hours of battery life did not disappoint.

Andrew Mitsi

STYLISTIC Q702

The screen was particularly good. It is bright and visible from most angles, however heat is an issue, particularly around the Windows button on the front, and on the back where the battery housing is located.

Simon Harriott

STYLISTIC Q702

My first impression after unboxing the Q702 is that it is a nice looking unit. Styling is somewhat minimalist but very effective. The tablet part, once detached, has a nice weight, and no buttons or switches are located in awkward or intrusive positions.

Resources

Best Deals on GoodGearGuide

Latest Jobs

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?