cbcvebase.
CVE-2001-1021
published 2001-07-26

CVE-2001-1021: Buffer overflows in WS_FTP 2.02 allow remote attackers to execute arbitrary code via long arguments to (1) DELE, (2) MDTM, (3) MLST, (4) MKD, (5) RMD, (6)…

PriorityP341high7.5CVSS 2.0
AVNACLAuNCPIPAP
EXPLOIT
EPSS
42.14%
98.5th percentile
Buffer overflows in WS_FTP 2.02 allow remote attackers to execute arbitrary code via long arguments to (1) DELE, (2) MDTM, (3) MLST, (4) MKD, (5) RMD, (6) RNFR, (7) RNTO, (8) SIZE, (9) STAT, (10) XMKD, or (11) XRMD.

Affected

1 ranges
VendorProductVersion rangeFixed in
progressws_ftp_server

Detection & IOCsextracted from sources · hover to see the quote

commandDELE <payload of 460+ bytes>
commandRNFR <768 bytes of 'A'>
filenamedefcom.iyd
bytes
\x8b\xd8\x8b\xf8\x83\xc0\x18\x33\xc9\x66\xb9\x42\x81\x66\x81\xf1\x80\x80\x80\x30\x95\x40\xe2\xfa\xde\x1e\x76\x1e\x7e\x2e\x95\x6f\x95\x95\xc6\xfd\xd5\x95\x95\x95\x2b\x49\x81\xd0\x95\x6a\x83\x96\x56\x1e\x75\x1e\x7d\xa6\x55\xc5\xfd\x15\x95\x95\x95\xff\x97\xc5\xc5\xfd\x95\x95\x95\x85\x14\x52\x59\x94\x95\x95\xc2\x2b\xb1\x80\xd0\x95\x6a\x83\xc5\x2b\x6d\x81\xd0\x95\x6a\x83\xa6\x55\xc5\x2b\x85\x83\xd0\x95\x6a\x83
snort
alert ftp $EXTERNAL_NET any -> $HOME_NET any (msg:"GPL FTP RMD overflow attempt"; flow:established,to_server; content:"RMD"; nocase; isdataat:100,relative; pcre:"/^RMD\s[^\n]{100}/smi"; reference:bugtraq,2972; reference:cve,2000-0133; reference:cve,2001-0826; reference:cve,2001-1021; classtype:attempted-admin; sid:2101976; rev:11;)
snort
alert ftp $EXTERNAL_NET any -> $HOME_NET any (msg:"GPL FTP invalid MDTM command attempt"; flow:established,to_server; content:"MDTM"; fast_pattern; nocase; pcre:"/^MDTM \d+[-+]\D/smi"; reference:bugtraq,9751; reference:cve,2001-1021; reference:cve,2004-0330; classtype:attempted-admin; sid:2102416; rev:9;)
snort
alert tcp $EXTERNAL_NET any -> $HOME_NET 21 (msg:"GPL FTP RNTO overflow attempt"; flow:established,to_server; content:"RNTO"; nocase; isdataat:100,relative; pcre:"/^RNTO\s[^\n]{100}/smi"; reference:bugtraq,8315; reference:cve,2000-0133; reference:cve,2001-1021; reference:cve,2003-0466; classtype:attempted-admin; sid:2102389; rev:9;)
snort
alert ftp $EXTERNAL_NET any -> $HOME_NET any (msg:"GPL FTP MDTM overflow attempt"; flow:established,to_server; content:"MDTM"; nocase; isdataat:100,relative; pcre:"/^MDTM\s[^\n]{100}/smi"; reference:bugtraq,9751; reference:cve,2001-1021; reference:cve,2004-0330; reference:nessus,12080; classtype:attempted-admin; sid:2102546; rev:8;)
  • FTP commands DELE, MDTM, MLST, MKD, RMD, RNFR, RNTO, SIZE, STAT, XMKD, XRMD with arguments exceeding ~100 bytes should be flagged as potential buffer overflow attempts against WS_FTP Server.
  • Exploit authenticates anonymously (user: ftp / pass: ftp) before sending the overflow payload; monitor for anonymous FTP logins immediately followed by oversized command arguments.
  • RNFR overflow requires a payload of 768 bytes; alert on RNFR arguments >= 768 bytes on TCP/21.
  • DELE overflow payload is padded to 460+ bytes with \xd4 NOP-sled followed by a return address; alert on DELE arguments >= 460 bytes.
  • Successful exploitation results in arbitrary code running with SYSTEM privilege; look for the WS_FTP server process spawning unexpected child processes.
  • MDTM anomaly detection: flag MDTM commands where the argument matches the pattern of a numeric timestamp followed by a sign character and a non-digit (malformed timezone offset used in exploitation).
  • ·The RMD and RNTO Snort rules reference additional CVEs (CVE-2000-0133, CVE-2001-0826, CVE-2003-0466) beyond CVE-2001-1021; tune rule metadata/references to scope detections specifically to WS_FTP if deployed in mixed-vendor FTP environments to reduce false positives.
  • ·The MDTM overflow rule (sid:2102546) and the MDTM invalid-command rule (sid:2102416) both cover CVE-2001-1021 but use different PCRE patterns; deploy both to cover both the length-based and malformed-argument attack vectors.
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