[ISN] Another big Apache hole found

From: InfoSec News (isn@private)
Date: Wed Jun 30 2004 - 07:23:29 PDT

  • Next message: InfoSec News: "[ISN] US-CERT: Beware of IE"

    By Matthew Broersma
    JUNE 28, 2004
    LONDON - Linux and Unix vendors are releasing fixes for a critical bug
    in the popular Web server Apache that could allow attackers to crash
    the system or execute malicious code.
    The bug affects Apache 1.3.x installations configured to act as proxy
    servers, which relay requests between a Web browser and the Internet.  
    When a vulnerable server connects to a malicious site, a specially
    crafted packet can be used to exploit the vulnerability, according to
    security researcher Georgi Guninski, who has publicly released exploit
    The bug is most serious on BSD installations, where it may allow code
    execution, while on other platforms the most likely effect is a system
    crash, researchers said. A reference in the Common Vulnerabilities and
    Exposures database can be found here.
    Guninski released information about the proxy-server bug earlier this
    month, and last month discovered a similar vulnerability in an Apache
    component offering Secure Sockets Layer encryption, but he said the
    bugs don't reflect on Apache's overall security relative to
    competitors such as Microsoft's Internet Information Services. "Still
    Apache is much better than Windows," he said in an advisory.
    Debian released a patch for the bug today, and Gentoo Linux released
    its own patch last week. Red Hat Inc., OpenBSD and OpenPKG have also
    released updates fixing the bug, while Novell Inc.'s Suse Linux said
    in an advisory last week it is testing a patch. Researchers said
    Apple's BSD-based Mac OS X is likely affected, but Apple has not yet
    released a patch.
    Apache versions 1.3.31, 1.3.29, 1.3.28, 1.3.27 and 1.3.26 are
    affected, while the bug has been fixed in 1.3.32-dev, according to
    security experts. System administrators can also get around the
    problem by switching off Apache's proxy-server module.
    "If I were running a BSD system, I would be very careful with this,"  
    said Thomas Kristensen, CTO of Secunia, which maintains a database
    tracking vulnerability advisories. "It's important to note that the
    potential for code execution has not been proven to be exploitable,
    but it pays to be safe." BSD is frequently used by Web hosting
    companies, he said.
    Kristensen said that despite the recent bugs, Apache's security is
    solid overall. Both Apache and IIS have been so thoroughly studied
    that few vulnerabilities are now discovered in their core components,
    he said - with both servers, problems are now mostly found in
    extensions such as mod_ssl and mod_proxy. "It's pretty solid as long
    as you remember to configure it correctly and to disable the
    extensions that are not necessary for your business," Kristensen said.
    The bug in Apache's mod_proxy module means that a negative
    user-specified length value may be used in a memory copy operation,
    leading to corruption of memory and a buffer overflow. The exploit can
    take effect when a remote server sends a negative Content-Length: HTTP
    header field to the proxy server.
    The proxy bug is the sixth vulnerability in Apache 1.3.x reported this
    year, according to Secunia, which has recorded 10 such advisories in
    2003 and 2004. Half of these were moderately or highly critical,
    usually meaning they allowed remote access to the system or denial of
    service. For comparison, IIS 5.x also had 10 advisories in the same
    period, 40% of which were highly or extremely critical, Secunia said.
    In 2002, the Slapper worm took advantage of a month-old bug in
    Apache's mod_ssl component, causing widespread disruption.
    ISN mailing list
    Sponsored by: OSVDB.org - For 15 cents a day, you could help feed an InfoSec junkie!
    (Broke? Spend 15 minutes a day on the project!)

    This archive was generated by hypermail 2b30 : Wed Jun 30 2004 - 15:24:28 PDT