Feeds

LSD puts Sendmail bug under the microscope

Proof of concept

  • alert
  • submit to reddit

Securing Web Applications Made Simple and Scalable

Polish ethical hackers Last Stage of Delirium (LSD) yesterday published proof of concept code for a serious flaw in Sendmail which emerged this week.

In a posting to BugTraq yesterday, LSD provides a detailed analysis of the buffer overflow vulnerability for the first time.

Previous advisories on the flaw, which has been present in Sendmail (undiscovered) for some years, are noticeably lacking in detail.

The vulnerability resides within the crackaddr(char* addr) function of the headers.c file, according to LSD's research. Ironically this function is designed to be a security mechanism.

Based on their preliminary work the Poles tentatively suggest the Sendmail vulnerability is less bad than
it first appeared.

"Due to the nature of the discussed Sendmail vulnerability it seems that it is unexploitable on most of commercially available UNIX systems," LSD writes. "It also doesn't seem to be exploitable on most of the default SMTP installations of x86 based open-source systems.

"This leads to the conclusion that the overall impact of the vulnerability is rather limited and not so significant as it might be thought," the group adds.

By its own admission, LSD's analysis is not exhaustive, testing only for one possible exploit mechanism on Unix and (Slackwave and Red Hat) Linux servers. So don't read too much into the group's conclusions just yet.

"We cannot exclude that there does not exist another execution path in the Sendmail code, that could lead to the program counter overwrite," LSD writes.

In a follow-up post, Sendmail's Eric Allman points out patches still need to be applied.

"Please don't breath a sigh of relief because you are running on one of the 'does not crash' systems," he writes.

"Besides direct execution path exploits, there are other variables that are not pointers that have security implications; finding one of them within range will be more difficult, but probably not impossible." ®

Related Stories

Sendmail vuln. Patch now
Slammer: Why security benefits from proof of concept code
Open and closed security are roughly equivalent
FBI names 20 most unwanted security flaws

External Links

CERT advisory: Remote Buffer Overflow in Sendmail
Patch application and testing tool from Sendmail

The smart choice: opportunity from uncertainty

More from The Register

next story
BMW's ConnectedDrive falls over, bosses blame upgrade snafu
Traffic flows up 20% as motorway middle lanes miraculously unclog
Putin: Crack Tor for me and I'll make you a MILLIONAIRE
Russian Interior Ministry offers big pile o' roubles for busting pro-privacy browser
Mozilla fixes CRITICAL security holes in Firefox, urges v31 upgrade
Misc memory hazards 'could be exploited' - and guess what, one's a Javascript vuln
Manic malware Mayhem spreads through Linux, FreeBSD web servers
And how Google could cripple infection rate in a second
How long is too long to wait for a security fix?
Synology finally patches OpenSSL bugs in Trevor's NAS
Don't look, Snowden: Security biz chases Tails with zero-day flaws alert
Exodus vows not to sell secrets of whistleblower's favorite OS
Roll out the welcome mat to hackers and crackers
Security chap pens guide to bug bounty programs that won't fail like Yahoo!'s
prev story

Whitepapers

Top three mobile application threats
Prevent sensitive data leakage over insecure channels or stolen mobile devices.
Implementing global e-invoicing with guaranteed legal certainty
Explaining the role local tax compliance plays in successful supply chain management and e-business and how leading global brands are addressing this.
Boost IT visibility and business value
How building a great service catalog relieves pressure points and demonstrates the value of IT service management.
Designing a Defense for Mobile Applications
Learn about the various considerations for defending mobile applications - from the application architecture itself to the myriad testing technologies.
Build a business case: developing custom apps
Learn how to maximize the value of custom applications by accelerating and simplifying their development.