cbcvebase.
CVE-2011-3200
published 2011-09-06

CVE-2011-3200: Stack-based buffer overflow in the parseLegacySyslogMsg function in tools/syslogd.c in rsyslogd in rsyslog 4.6.x before 4.6.8 and 5.2.0 through 5.8.4 might…

PriorityP337medium5CVSS 2.0
AVNACLAuNCNINAP
EXPLOIT
EPSS
20.76%
97.2th percentile
Stack-based buffer overflow in the parseLegacySyslogMsg function in tools/syslogd.c in rsyslogd in rsyslog 4.6.x before 4.6.8 and 5.2.0 through 5.8.4 might allow remote attackers to cause a denial of service (application exit) via a long TAG in a legacy syslog message.

Affected

56 ranges· showing 25
VendorProductVersion rangeFixed in
debianrsyslog< rsyslog 5.8.5-1 (bookworm)rsyslog 5.8.5-1 (bookworm)
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Detection & IOCsextracted from sources · hover to see the quote

processrsyslogd
pathtools/syslogd.c
  • Detect exploitation attempts by monitoring for syslog messages with a TAG field of 512 or more characters sent to UDP/TCP syslog port; the overflow writes '\0' or ':\0' past the 512-byte bufParseTAG array boundary.
  • Monitor rsyslogd process for sudden termination preceded by a glibc 'stack smashing detected' message, which is the observable crash signature on ia-32 (RHEL6) systems.
  • The vulnerability is remotely triggerable if rsyslogd is configured to receive messages over UDP or TCP; an attacker can send the malformed message using netcat from a remote host.
  • Affected versions are rsyslog 4.6.0–4.6.7 and 5.2.0–5.8.4; the bug was introduced in 4.6.0 and corrected in 4.6.8/5.8.5. Focus detection on hosts running these version ranges.
  • On x86-64 the stack guard variable is located 8 bytes above bufParseTAG, so the overflow may not reach it; the bug is most reliably triggered on ia-32 (32-bit) systems such as RHEL6 i686.
  • A Metasploit auxiliary module (dos/syslog/rsyslog_long_tag) exists for this vulnerability; detect or block exploitation attempts from known Metasploit framework user-agents or scanning patterns targeting syslog ports.
  • ·The vulnerability is only exploitable remotely if rsyslogd is explicitly configured to accept messages over UDP or TCP; default local-only configurations are not remotely reachable.
  • ·RHEL5 is not affected because its rsyslog code does not use a stack-allocated buffer with an index variable for TAG parsing; it uses a malloc-allocated buffer accessed via pointer increment.
  • ·Compiler differences (e.g., stack layout on x86-64 vs ia-32) may prevent the overflow from reaching the SSP guard cookie, meaning the bug may cause no noticeable result on many systems.
  • ·The overflow is limited to writing '\0' or ':\0' past the buffer boundary; arbitrary code execution is not considered feasible because SSP mitigates to crash-only and all other local variables are placed below the buffer by gcc.

CVSS provenance

nvdv2.05.0MEDIUMAV:N/AC:L/Au:N/C:N/I:N/A:P
osv5.0MEDIUM
vendor_debian5.0LOW
vendor_redhat5.0MEDIUM
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