cbcvebase.
CVE-2001-1013
published 2001-09-12

CVE-2001-1013: Apache on Red Hat Linux with with the UserDir directive enabled generates different error codes when a username exists and there is no public_html directory…

PriorityP335medium5CVSS 2.0
AVNACLAuNCPINAN
EXPLOIT
EPSS
65.56%
99.2th percentile
Apache on Red Hat Linux with with the UserDir directive enabled generates different error codes when a username exists and there is no public_html directory and when the username does not exist, which could allow remote attackers to determine valid usernames on the server.

Affected

1 ranges
VendorProductVersion rangeFixed in
redhatlinux

Detection & IOCsextracted from sources · hover to see the quote

urlhttp://www.example.com/~<username>
path/~$user
commandGET /~<username> HTTP/1.0
  • Detect username enumeration attempts via HTTP GET requests to /~<username> paths; a 403 response ('You don't have permission') indicates a valid user without a public_html directory, while a 404 ('not found') indicates no such user.
  • Monitor for sequential or high-volume HTTP GET requests matching the pattern /~<word> from a single source IP, indicative of automated username enumeration using a wordlist.
  • Alert on HTTP responses containing the string 'permission' in reply to /~<username> requests, as the exploit script specifically sniffs for this keyword to confirm valid usernames.
  • ·The UserDir directive must be enabled in Apache for this vulnerability to be exploitable; it is disabled by default on Red Hat Enterprise Linux 5, 6, and 7.
  • ·Mitigation is possible without disabling UserDir entirely: configure httpd to return a single, uniform custom error code/page regardless of whether the username exists, eliminating the differential response that enables enumeration.

CVSS provenance

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