Patchfirst
CVE-2018-20250 KEVRansomwarePublic exploit High · 7.8 EPSS 96.0%

WinRAR Absolute Path Traversal Vulnerability

RARLAB · WinRAR

Summary

WinRAR (by RARLAB) contains an absolute path traversal flaw in its handling of the filename field in ACE-format archives, implemented in the UNACEV2.dll component, affecting versions up to and including 5.61. When a specially crafted filename is processed, WinRAR ignores the chosen extraction folder and treats the filename as an absolute path, so an attacker who can get a user to open a malicious ACE archive (local access, user interaction required, no authentication) can cause files to be written to arbitrary locations.

Official description · NVD

In WinRAR versions prior to and including 5.61, There is path traversal vulnerability when crafting the filename field of the ACE format (in UNACEV2.dll). When the filename field is manipulated with specific patterns, the destination (extraction) folder is ignored, thus treating the filename as an absolute path.

Breakdown
86.2 / 100
Exploited
Yes, in CISA KEV
Reports
3
Tactics
2/15

How an attack unfolds

Based on mappings. Select a step to see the evidence.
  1. What they do

  2. What can follow

First seen exploited 23 days after disclosure. Public exploit code (Metasploit) was available the same day.

  1. DisclosedPublic exploit codeMetasploitday 0
  2. First seen exploitedVulnCheck KEV evidence+23 days
  3. Named in a threat reportmicrosoft.com+16 mo
  4. Added to CISA KEVknown ransomware use; EU database agrees+3 yrs

CISA KEV listing is when exploitation was confirmed, not necessarily the first attack.

techniques

2 , grouped by in kill-chain order, 2 cited passages 11

ExecutionTA0002

Malicious File T1204.002 Medium
MITRE CTID mapping of the CVE · uncategorised

Stealth

Masquerading T1036 Medium
AI mapping from the description · primary impact

Attacker-controlled absolute path writes files outside intended folder

the destination (extraction) folder is ignored, thus treating the filename as an absolute path
From the official description (NVD) Original (opens in a new tab) ↗
Lower-confidence links (1)

These come from early or generic mappings, text matching, or contradict this CVE’s details (for example a public-facing technique on a bug that needs a user to open a file). Shown for completeness.

  • Exploitation for Client ExecutionT1203 CTID attack_to_cve Phase 1 "Uncategorized" mapping (not staged by impact)

Detection

0 rules for this CVE · 79 general rules for its techniques

Rules for this CVE

0 that reference CVE-2018-20250 directly.

CVE-specific rules are not available in this build. Search SigmaHQ ↗

Sigma rules © SigmaHQ, Detection Rule License 1.1; linked, not reproduced.

What security researchers reported

Named in 3 threat reports
3 reportsMicrosoftSymantecclearskysec.comJun 2020 · 2 undated

Reports are matched by finding the exact id CVE-2018-20250 in their text; nobody has reviewed the match. One passage is shown per report, at most 320 characters, linked to the original.

Also mentioned in 50 community threat pulses (AlienVault OTX)

Weaker evidence

Pulses are indicator collections that anyone can publish. A mention is not confirmation of exploitation.

References

9 links, grouped by NVD tag (8 duplicates merged)
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